Organic electroluminescent element and electronic device

ABSTRACT

An organic electroluminescence device includes: an anode; an emitting layer; and a cathode, the emitting layer containing a first material, a second material and a third material, the first material being a fluorescent material, the second material being a delayed fluorescent material, the third material having a singlet energy larger than a singlet energy of the second material.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of prior U.S. application Ser.No. 17/009,059, filed Sep. 1, 2020, the disclosure of which isincorporated herein by reference in its entirety. U.S. application Ser.No. 17/009,059 is a continuation of U.S. patent application Ser. No.15/866,616, filed Jan. 10, 2018, issued as U.S. Pat. No. 10,811,616 onOct. 20, 2020, the disclosure of which is incorporated herein byreference in its entirety. U.S. patent application Ser. No. 15/866,616is a continuation of U.S. patent application Ser. No. 14/777,679 filedon Sep. 16, 2015, issued as U.S. Pat. No. 9,905,779 on Feb. 27, 2018,the disclosure of which is incorporated herein by reference in itsentirety. U.S. patent application Ser. No. 14/777,679 is a 35 U.S.C. §371 national stage patent application of international patentapplication PCT/JP2014/084175, filed on Dec. 24, 2014, which claimspriority to Japanese patent application JP 2014-052133, filed on Mar.14, 2014, and Japanese patent application JP 2013-270267, filed on Dec.26, 2013, the disclosures of which are incorporated herein by referencein their entireties.

TECHNICAL FIELD

The present invention relates to an organic electroluminescence deviceand an electronic device.

BACKGROUND ART

When a voltage is applied to an organic electroluminescence device(hereinafter, occasionally referred to as “organic EL device”), holesand electrons are injected into an emitting layer respectively from ananode and a cathode. The injected holes and electrons are recombined togenerate excitons in the emitting layer. According to the electron spinstatistics theory, singlet excitons and triplet excitons are generatedat a ratio of 25%:75%.

A fluorescent organic EL device, which uses emission caused by singletexcitons, is inferred to exhibit an internal quantum efficiency of 25%at a maximum. Although having been used in full-color displays of amobile phone, TV and the like, a fluorescent EL device is required touse triplet excitons in addition to singlet excitons to further enhanceefficiency.

In view of the above, a highly efficient fluorescent organic EL deviceusing delayed fluorescence has been studied.

For instance, a thermally activated delayed fluorescence (TADF)mechanism has been studied. The TADF mechanism uses such a phenomenonthat inverse intersystem crossing from triplet excitons to singletexcitons thermally occurs when a material having a small energydifference (ΔST) between singlet energy level and triplet energy levelis used. As for thermally activated delayed fluorescence, refer to, forinstance, “ADACHI, Chihaya, ed. (Mar. 22, 2012), Yuki Hando-tai noDebaisu Bussei (Device Physics of Organic Semiconductors), Kodansha, pp.261-262.”

For instance, Patent Literatures 1 to 3 disclose organic EL devicesusing the TADF mechanism.

Patent Literature 1 discloses an organic EL device including an emittinglayer that contains a compound with a small ΔST as a host material and afluorescent compound as a dopant material. According to PatentLiterature 1, when the TADF mechanism is generated by using a compoundwith a small Δ ST as a host material, the internal quantum efficiency isimproved.

Patent Literatures 2 and 3 also each disclose an organic EL deviceincluding an emitting layer that contains a specific compound with asmall ΔST as a host material and a fluorescent compound as a dopantmaterial. In Patent Literatures 2 and 3, the TADF mechanism is used toimprove the performance of the organic EL device as in Patent Literature1.

CITATION LIST Patent Literature(s)

Patent Literature 1: International Publication No. WO2012/133188

Patent Literature 2: International Publication No. WO2013/180241

Patent Literature 3: Chinese Patent Application Publication No.102709485

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, further improvement of an organic EL device in luminousefficiency is still demanded.

An object of the invention is to provide an organic electroluminescencedevice with improved luminous efficiency. Another object of theinvention is to provide an electronic device provided with the organicelectroluminescence device.

Means for Solving the Problems

According to an aspect of the invention, an organic electroluminescencedevice includes: an anode; an emitting layer; and a cathode, theemitting layer containing a first material, a second material and athird material, the first material being a fluorescent material, thesecond material being a delayed fluorescent material, the third materialhaving a singlet energy larger than a singlet energy of the secondmaterial.

According to another aspect of the invention, an electronic deviceincludes the organic electroluminescence device according to the aboveaspect.

The above aspect of the invention can provide an organicelectroluminescence device with improved luminous efficiency.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 schematically shows an exemplary arrangement of an organicelectroluminescence device according to an exemplary embodiment.

FIG. 2 schematically shows a device for measuring transient PL.

FIG. 3 shows examples of a transient PL decay curve.

FIG. 4 shows a relationship of energy levels of first, second and thirdmaterials in an emitting layer and energy transfer thereamong.

DESCRIPTION OF EMBODIMENTS

An organic EL device according to an exemplary embodiment of theinvention will be described below.

First Exemplary Embodiment Arrangement(s) of Organic EL Device

Arrangement(s) of an organic EL device according to a first exemplaryembodiment will be described below.

The organic EL device includes a pair of electrodes and an organic layerdisposed between the electrodes. The organic layer includes a pluralityof layers formed of an organic compound. The organic layer may furthercontain an inorganic compound.

The organic layer of the organic EL device of the exemplary embodimentincludes at least one emitting layer. Specifically, for instance, theorganic layer may consist of a single emitting layer, or may includelayers usable in a typical organic EL device, such as a hole injectinglayer, a hole transporting layer, an electron injecting layer, anelectron transporting layer and a blocking layer.

FIG. 1 schematically shows an exemplary arrangement of an organic ELdevice according to the exemplary embodiment.

An organic EL device 1 includes a light-transmissive substrate 2, ananode 3, a cathode 4, and an organic layer 10 provided between the anode3 and the cathode 4.

The organic layer 10 includes an emitting layer 5, a holeinjecting/transporting layer 6 provided between the emitting layer 5 andthe anode 3, and an electron injecting/transporting layer 7 providedbetween the emitting layer 5 and the cathode 4. In the organic EL deviceof the exemplary embodiment, the emitting layer 5 contains first, secondand third materials. The emitting layer 5 may contain a phosphorescentmetal complex. However, the organic EL device of the exemplaryembodiment can exhibit an emitting performance superior to that of atypical fluorescent organic EL device even when the emitting layer 5contains no phosphorescent metal complex.

The term “hole injecting/transporting layer” means at least one of ahole injecting layer and a hole transporting layer. The term “electroninjecting/transporting layer” means at least one of an electroninjecting layer and an electron transporting layer. Herein, when thehole injecting layer and the hole transporting layer are provided, thehole injecting layer is preferably provided between the anode and thehole transporting layer. When the electron injecting layer and theelectron transporting layer are provided, the electron injecting layeris preferably provided between the cathode and the electron transportinglayer. The hole injecting layer, the hole transporting layer, theelectron transporting layer and the electron injecting layer may eachconsist of a single layer or may alternatively include a plurality oflaminated layers.

Emitting Layer First Material

In the exemplary embodiment, the first material is a fluorescentmaterial.

The first material is not necessarily particularly limited, especially,in terms of luminescent color, but preferably emits a fluorescent lightwith a main peak wavelength of 550 nm or less, and more preferably emitsa fluorescent light with a main peak wavelength of 480 nm or less.Especially, although a typical blue-emitting organic EL device entails aproblem of improvement in luminous efficiency, the organic EL device ofthe exemplary embodiment is inferred to emit a blue light with anexcellent luminous efficiency.

A main peak wavelength means a peak wavelength of luminescence spectrumexhibiting a maximum luminous intensity among luminous spectra measuredusing a toluene solution where the main material is dissolved at aconcentration from 10⁻⁵ mol/l to 10⁻⁶ mol/l.

The first material preferably emits a blue fluorescent light. The firstmaterial preferably exhibits a high fluorescence quantum efficiency.

The first material of the exemplary embodiment may be a fluorescentmaterial. Specific examples of the fluorescent material include abisarylaminonaphthalene derivative, aryl-substituted naphthalenederivative, bisarylaminoanthracene derivative, aryl-substitutedanthracenederivative, bisarylaminopyrene derivative, aryl-substitutedpyrene derivative, bisarylaminochrysene derivative, aryl-substitutedchrysene derivative, bisarylaminofluoranthene derivative,aryl-substituted fluoranthene derivative, indenoperylene derivative,acenaphthofluoranthene derivative, pyrromethene boron complex compound,compound having a pyrromethene skeleton, metal complex of a compoundhaving a pyrromethene skeleton, diketopyrolopyrrol derivative, perylenederivative, and naphthacene derivative.

The first material of the exemplary embodiment may be a compoundrepresented by a formula (10) below.

In the formula (10), A_(D) is a substituted or unsubstituted aromatichydrocarbon group having 12 to 50 carbon atoms forming the aromatic ring(i.e., ring carbon atoms). Examples of the aromatic hydrocarbon grouphaving 12 to 50 ring carbon atoms for A_(D) include groups derived fromnaphthalene, anthracene, benzanthracene, phenanthrene, chrysene, pyrene,fluoranthene, benzofluoranthene, perylene, picene, triphenylene,fluorene, benzofluorene, stilbene, naphthacene andacenaphthofluoranthene. A_(D) may be a benzo group or a ring-expandedgroup prepared from an aromatic hydrocarbon having 12 to 50 ring carbonatoms.

In the formula (10), B_(D) is represented by a formula (11) below.

In the formula (10), pa is an integer of 1 to 4, and pb is an integer of0 to 4.

In the formula (11), Ar₁, Ar₂ and Ar₃ each independently represent asubstituent selected from the group consisting of a substituted orunsubstituted aromatic hydrocarbon group having 6 to 50 ring carbonatoms, substituted or unsubstituted alkyl group having 1 to 50 carbonatoms, substituted or unsubstituted alkenyl group, substituted orunsubstituted alkynyl group, and substituted or unsubstitutedheterocyclic group having 5 to 50 atoms forming a ring (i.e., ringatoms), and pc is an integer of 0 to 4. A wavy line in the formula (11)shows a bonding position with the aromatic hydrocarbon group representedby A_(D).

In the formulae (10) and (11), a plurality of A_(D) may be mutually thesame or different, a plurality of B_(D) may be mutually the same ordifferent, a plurality of Ar₁ may be mutually the same or different, aplurality of Ar₂ may be mutually the same or different, a plurality ofAr₃ may be mutually the same or different, and a plurality of pc may bemutually the same or different.

Examples of the compound represented by the formula (10) include thefollowing compounds, but the first material is not limited thereto. Inthe following compounds, A_(D1) to A_(D4) each independently representthe same as A_(D), and B_(D1) to B_(D4) each independently represent thesame as B_(D).

The aromatic hydrocarbon group for A_(D) is preferably an aromatichydrocarbon group having 12 to 30 ring carbon atoms, more preferably anaromatic hydrocarbon group having 12 to 24 ring carbon atoms, andfurther preferably an aromatic hydrocarbon having 18 to 20 ring carbonatoms. Examples of the aromatic hydrocarbon group for A_(D) include anaphthylphenyl group, naphthyl group, acenaphthylenyl group, anthrylgroup, benzoanthryl group, aceanthryl group, phenanthryl group,benzo[c]phenanthryl group, phenalenyl group, fluorenyl group, picenylgroup, pentaphenyl group, pyrenyl group, chrysenyl group,benzo[g]chrysenyl group, s-indacenyl group, as-indacenyl group,fluoranthenyl group, benzo[k]fluoranthenyl group, triphenylenyl group,benzo[b]triphenylenyl group, benzofluorenyl group, styrylphenyl group,naphthacenyl group and perylenyl group, and benzo groups andring-expanded groups of these groups. The aromatic hydrocarbon group forA_(D) is preferably any one of an anthryl group, picenyl group, pyrenylgroup, chrysenyl group, fluoranthenyl group, benzo[k]fluoranthenylgroup, benzofluorenyl group, styrylphenyl group, naphthacenyl group andperylenyl group, and benzo groups and ring-expanded groups of thesegroups, more preferably any one of an anthryl group, pyrenyl group,chrysenyl group, benzo[k]fluoranthenyl group, benzofluorenyl group,styrylphenyl group and acenaphtho[1,2-k]fluoranthenyl group, and benzogroups and ring-expanded groups of these groups, and especiallypreferably any one of an anthryl group, pyrenyl group, chrysenyl group,benzo[k]fluoranthenyl group, benzofluorenyl group,acenaphtho[1,2-k]fluoranthenyl group and naphthacenyl group.

The aromatic hydrocarbon group(s) (hereinafter, occasionally referred toas aryl group) for Ar₁, Ar₂ and Ar₃ is preferably each independently anaromatic hydrocarbon group having 6 to 24 ring carbon atoms, and morepreferably an aromatic hydrocarbon group having 6 to 12 ring carbonatoms. The aromatic hydrocarbon group(s) for Ar₁, Ar₂ and Ar₃ may eachindependently be any one of a phenyl group, naphthylphenyl group,biphenylyl group, terphenylyl group, naphthyl group, acenaphthylenylgroup, anthryl group, benzoanthryl group, aceanthryl group, phenanthrylgroup, benzo[c]phenanthryl group, phenalenyl group, fluorenyl group,picenyl group, pentaphenyl group, pyrenyl group, chrysenyl group,benzo[g]chrysenyl group, s-indacenyl group, as-indacenyl group,fluoranthenyl group, benzo[k]fluoranthenyl group, triphenylenyl group,benzo[b]triphenylenyl group, benzofluorenyl group, styrylphenyl group,naphthacenyl group and perylenyl group, and benzo groups andring-expanded groups of these groups, among which a phenyl group,biphenyl group, terphenylyl group and naphthyl group are preferable,phenyl group, biphenyl group and terphenylyl group are more preferable,and a phenyl group is especially preferable.

Examples of the substituted aromatic hydrocarbon group include aphenylnaphthyl group, naphthylphenyl group, tolyl group, xylyl group,silylphenyl group, trimethylsilylphenyl group, 9,9-dimethylfluorenylgroup, 9,9-diphenylfluorenyl group, 9,9′-spirobifluorenyl group andcyanophenyl group, among which, for instance, a tolyl group, xylylgroup, trimethylsilylphenyl group, 9,9-dimethylfluorenyl group,9,9-diphenylfluorenyl group, 9,9′-spirobifluorenyl group, cyanophenylgroup and silylphenyl group are preferable.

The alkyl group(s) for Ar₁, Ar₂ and Ar₃ is preferably each independentlyan alkyl group having 1 to 10 carbon atoms, and more preferably an alkylgroup having 1 to 5 carbon atoms. Examples of the alkyl group(s) for Ar₁and Ar₂ include a methyl group, ethyl group, n-propyl group, isopropylgroup, n-butyl group, isobutyl group, s-butyl group, t-butyl group,pentyl group (including isomers thereof), hexyl group (including isomersthereof), heptyl group (including isomers thereof), octyl group(including isomers thereof), nonyl group (including isomers thereof),decyl group (including isomers thereof), undecyl group (includingisomers thereof) and dodecyl group (including isomers thereof), amongwhich a methyl group, ethyl group, n-propyl group, isopropyl group,n-butyl group, isobutyl group, s-butyl group, t-butyl group and pentylgroup (including isomers thereof) are preferable, a methyl group, ethylgroup, n-propyl group, isopropyl group, n-butyl group, isobutyl group,s-butyl group and t-butyl group are more preferable, and a methyl group,ethyl group, isopropyl group and t-butyl group are especiallypreferable.

The alkyl group(s) for Ar₁, Ar₂ and Ar₃ may each independently be acycloalkyl group having 3 to 50 ring carbon atoms. The cycloalkylgroup(s) for Ar₁, Ar₂ and Ar₃ is preferably each independently acycloalkyl group having 3 to 6 ring carbon atoms, and more preferably acycloalkyl group having 5 or 6 ring carbon atoms. Examples of thecycloalkyl group(s) for Ar₁, Ar₂ and Ar₃ include a cyclopropyl group,cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptylgroup, cyclooctyl group and adamantyl group, among which a cyclopentylgroup and cyclohexyl group are preferable.

The alkenyl group(s) for Ar₁, Ar₂ and Ar₃ is preferably eachindependently an alkenyl group having 2 to 20 carbon atoms, and morepreferably an alkenyl group having 2 to 10 carbon atoms. Examples of thealkenyl group(s) for Ar₁, Ar₂ and Ar₃ include a vinyl group, allylgroup, 1-butenyl group, 2-butenyl group, 3-butenyl group,1,3-butanedienyl group, 1-methylvinyl group, 1-methylallyl group,1,1-dimethylallyl group, 2-methylallyl group and 1,2-dimethylallylgroup.

Examples of the substituted alkenyl group include a styryl group,2,2-diphenylvinyl group, 1,2-diphenylvinyl group, 1-phenylallyl group,2-phenylallyl group, 3-phenylallyl group, 3,3-diphenylallyl group,1-phenyl-1-butenyl group and 3-phenyl-1-butenyl group.

The alkynyl group(s) for Ar₁, Ar₂ and Ar₃ is preferably eachindependently an alkynyl group having 2 to 20 carbon atoms, and morepreferably an alkynyl group having 2 to 10 carbon atoms. The alkynylgroup(s) for Ar₁, Ar₂ and Ar₃ may be a propargyl group or a 3-pentynylgroup.

The heterocyclic group(s) for Ar₁, Ar₂ and Ar₃ is preferably eachindependently a heterocyclic group having 5 to 24 ring atoms, and morepreferably a heterocyclic group having 5 to 18 ring atoms. Theheterocyclic group(s) for Ar₁, Ar₂ and Ar₃ may be a heterocyclic grouphaving 1 to 5 hetero atoms. Examples of the hetero atom include nitrogenatom, oxygen atom and sulfur atom. The heterocyclic group(s) for Ar₁,Ar₂ and Ar₃ may each independently be any one of a pyrrolyl group, furylgroup, thienyl group, pyridyl group, pyridazynyl group, pyrimidinylgroup, pyrazinyl group, triazinyl group, imidazolyl group, oxazolylgroup, thiazolyl group, pyrazolyl group, isooxazolyl group, isothiazolylgroup, oxadiazolyl group, thiadiazolyl group, triazolyl group,tetorazolyl group, indolyl group, isoindolyl group, benzofuranyl group,isobenzofuranyl group, benzothiophenyl group, isobenzothiophenyl group,indolizinyl group, quinolizinyl group, quinolyl group, isoquinolylgroup, cinnoline group, phthalazinyl group, quinazolinyl group,quinoxalinyl group, benzimidazolyl group, benzoxazolyl group,benzothiazolyl group, indazolyl group, benzisoxazolyl group,benzisothiazolyl group, dibenzofuranyl group, dibenzothiophenyl group,carbazolyl group, phenanthridinyl group, acridinyl group,phenanthrolinyl group, phenazinyl group, phenothiazinyl group,phenoxazinyl group and xanthenyl group, among which a furyl group,thienyl group, pyridyl group, pyridazynyl group, pyrimidinyl group,pyrazinyl group, triazinyl group, benzofuranyl group, benzothiophenylgroup, dibenzofuranyl group and dibenzothiophenyl group are preferable,and a benzofuranyl group, benzothiophenyl group, dibenzofuranyl groupand dibenzothiophenyl group are more preferable.

Regarding the compound represented by the formula (10), an intendedsubstituent meant by “substituted or unsubstituted” is preferablyselected from the group consisting of an alkyl group having 1 to 50(preferably 1 to 10, more preferably 1 to 5) carbon atoms, an alkenylgroup having 2 to 20 (preferably 2 to 10) carbon atoms, an alkynyl grouphaving 2 to 20 (preferably 2 to 10) carbon atoms, a cycloalkyl having 3to 50 (preferably 3 to 6, more preferably 5 or 6) ring carbon atoms, anaromatic hydrocarbon group having 6 to 50 (preferably 6 to 24, morepreferably 6 to 12) ring carbon atoms, an aralkyl group having 1 to 50(preferably 1 to 10, more preferably 1 to 5) carbon atoms containing anaromatic hydrocarbon group having 6 to 50 (preferably 6 to 24, morepreferably 6 to 12) ring carbon atoms, an amino group, a monoalkylaminoor dialkylamino group having an alkyl group having 1 to 50 (preferably 1to 10, more preferably 1 to 5) carbon atoms, a monoarylamino ordiarylamino group having an aromatic hydrocarbon group having 6 to 50(preferably 6 to 24, and more preferably 6 to 12) ring carbon atoms, analkoxy group having an alkyl group having 1 to 50 (preferably 1 to 10,more preferably 1 to 5) carbon atoms, an aryloxy group having anaromatic hydrocarbon group having 6 to 50 (preferably 6 to 24, and morepreferably 6 to 12) ring carbon atoms, an alkylthio group having analkyl group having 1 to 50 (preferably 1 to 10, more preferably 1 to 5)carbon atoms, an arylthio group having an aromatic hydrocarbon grouphaving 6 to 50 (preferably 6 to 24, and more preferably 6 to 12) ringcarbon atoms, a monosubstituted, disubstituted or trisubstituted silylgroup having a group selected from an alkyl group having 1 to 50(preferably 1 to 10, more preferably 1 to 5) carbon atoms and anaromatic hydrocarbon group having 6 to 50 (preferably 6 to 24, morepreferably 6 to 12) ring carbon atoms, a heterocyclic group having 5 to50 (preferably 5 to 24, more preferably 5 to 18) ring atoms and 1 to 5(preferably 1 to 3, more preferably 1 or 2) hetero atoms (e.g., anitrogen atom, oxygen atom and sulfur atom), a haloalkyl group having 1to 50 carbon atoms (preferably 1 to 10, and more preferably 1 to 5carbon atoms), a halogen atom (e.g., a fluorine atom, chlorine atom,bromine atom or iodine atom, preferably a fluorine atom), a cyano group,and a nitro group.

Among the above substituents, a substituent selected from the groupconsisting of an alkyl group having 1 to 5 carbon atoms, cycloalkylgroup having 5 or 6 carbon atoms, aromatic hydrocarbon group having 6 to12 ring carbon atoms, and heterocyclic group having 5 to 24 ring atomsand 1 to 3 hetero atoms (at least one of a nitrogen atom, oxygen atomand sulfur atom) is particularly preferable.

The alkyl group having 1 to 50 carbon atoms meant by “substituted orunsubstituted” is the same as the alkyl group(s) for Ar₁, Ar₂ and Ar₃.The alkenyl group having 2 to 20 carbon atoms meant by “substituted orunsubstituted” is the same as the alkenyl group(s) for Ar₁, Ar₂ and Ar₃.

The alkynyl group having 2 to 20 carbon atoms meant by “substituted orunsubstituted” is the same as the alkynyl group(s) for Ar₁, Ar₂ and Ar₃.

The cycloalkyl group having 3 to 50 ring carbon atoms meant by“substituted or unsubstituted” is the same as the cycloalkyl group(s)for Ar₁, Ar₂ and Ar₃.

The aromatic hydrocarbon group having 6 to 50 ring carbon atoms meant by“substituted or unsubstituted” is the same as the aromatic hydrocarbongroup(s) for Ar₁, Ar₂ and Ar₃.

When the substituent meant by “substituted or unsubstituted” is anaralkyl group having 6 to 50 ring carbon atoms, the aralkyl groupcontains an aromatic hydrocarbon group having 6 to 50 ring carbon atomsand an alkyl group having 1 to 50 carbon atoms, and respective specificexamples of the alkyl group moiety and the aromatic hydrocarbon groupmoiety are the same as those of the above alkyl group and the abovearomatic hydrocarbon group.

When the substituent meant by “substituted or unsubstituted” is themonoalkylamino or dialkylamino group, specific examples of the alkylgroup moiety are the same as those of the above alkyl group.

When the substituent meant by “substituted or unsubstituted” is themonoarylamino or diarylamino group, specific examples of the aryl group(aromatic hydrocarbon group) moiety are the same as those of the abovearomatic hydrocarbon group.

When the substituent meant by “substituted or unsubstituted” is thealkoxy group, specific examples of the alkyl group moiety are the sameas those of the above alkyl group, and the alkoxy group is preferably,for instance, a methoxy group or an ethoxy group.

When the substituent meant by “substituted or unsubstituted” is thearyloxy group, specific examples of the aryl group (aromatic hydrocarbongroup) moiety are the same as those of the above aromatic hydrocarbongroup, and the aryloxy group may be a phenoxy group.

When the substituent meant by “substituted or unsubstituted” is thealkylthio group, specific examples of the alkyl group moiety are thesame as those of the above alkyl group.

When the substituent meant by “substituted or unsubstituted” is thearylthio group, specific examples of the aryl group (aromatichydrocarbon group) moiety are the same as those of the above aromatichydrocarbon group.

When the substituent meant by “substituted or unsubstituted” is themonosubstituted, disubstituted or trisubstituted silyl group, the silylgroup may be an alkylsilyl group having 1 to 50 carbon atoms or anarylsilyl group having 6 to 50 ring carbon atoms. Examples of thealkylsilyl group having 1 to 50 carbon atoms include a monoalkylsilylgroup, dialkylsilyl group and trialkylsilyl group. Specific examples ofeach alkyl group in the alkylsilyl group having 1 to 50 carbon atoms arethe same as those of the above alkyl group. Examples of the arylsilylgroup having 6 to 50 ring carbon atoms include a monoarylsilyl group,diarylsilyl group and triarylsilyl group. Specific examples of each arylgroup in the arylsilyl group having 6 to 50 ring carbon atoms, which arethe same as those of the above aryl group, may include a trimethylsilylgroup, triethylsilyl group, t-butyldimethylsilyl group,vinyldimethylsilyl group, propyldimethylsilyl group,isopropyldimethylsilyl group, triphenylsilyl group, phenyldimethylsilylgroup, t-butyldiphenylsilyl group and tritolylsilyl group.

When the substituent meant by “substituted or unsubstituted” is theheterocyclic group, the heterocyclic group is the same as thehetrocyclic group(s) for Ar₁, Ar₂ and Ar₃.

When the substituent meant by “substituted or unsubstituted” is thehaloalkyl group, the haloalkyl group may be a group obtained byhalogenating the above alkyl group, specific examples of which include atrifluoromethyl group.

The first material of the exemplary embodiment may be a compoundrepresented by a formula (12) below.

In the formula (12), R₁₁₀ to R₁₂₁ each independently represent ahydrogen atom or a substituent, the substituent being selected from thegroup consisting of a halogen atom, a cyano group, a substituted orunsubstituted alkyl group having 1 to 50 carbon atoms, a substituted orunsubstituted cycloalkyl group having 3 to 30 ring carbon atoms, asubstituted or unsubstituted alkenyl group having 2 to 20 carbon atoms,a substituted or unsubstituted alkynyl group having 2 to 20 carbonatoms, a substituted or unsubstituted alkoxy group having 1 to 50 carbonatoms, a substituted or unsubstituted alkylthio group having 1 to 50carbon atoms, a substituted or unsubstituted aryloxy group having 6 to50 ring carbon atoms, a substituted or unsubstituted arylthio grouphaving 6 to 50 ring carbon atoms, a substituted or unsubstitutedtrialkylsilyl group, a substituted or unsubstituted arylalkylsilylgroup, a substituted or unsubstituted triarylsilyl group, a substitutedor unsubstituted diarylphosphine oxide group, an amino group, amonoalkylamino or dialkylamino group having a substituted orunsubstituted alkyl group having 1 to 50 carbon atoms, a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms, and a substituted or unsubstituted heterocyclic group having 5 to30 ring atoms.

Second Material

In the exemplary embodiment, the second material is a delayedfluorescent material.

Delayed Fluorescence

Delayed fluorescence (thermally activated delayed fluorescence) isexplained in “ADACHI, Chihaya, ed., Yuki Hando-tai no Debaisu Bussei(Device Physics of Organic Semiconductors), Kodansha, pp. 261-268.”According to this literature, when an energy gap ΔE₁₃ between thesinglet state and the triplet state of a fluorescent material isreduced, inverse energy transfer from the triplet state, a lowtransition probability of which is usually low, to the singlet stateoccurs with a high efficiency to cause thermally activated delayedfluorescence (TADF). Further, FIG. 10.38 in this literature illustratesa mechanism for causing delayed fluorescence. The second material of theexemplary embodiment is a compound capable of thermally activateddelayed fluorescence caused by this mechanism.

Occurrence of delayed fluorescence emission can be determined bytransient PL measurement.

FIG. 2 schematically shows a device for measuring transient PL.

A transient PL measuring device 100 of the exemplary embodimentincludes: a pulse laser 101 capable of emitting light with apredetermined wavelength; a sample chamber 102 for housing a measurementsample; a spectrometer 103 that disperses light emitted from themeasurement sample; a streak camera 104 for forming a two-dimensionalimage; and a personal computer 105 that analyzes the two-dimensionalimage imported thereinto. It should be noted that transient PL may bemeasured by a device different from one described in the exemplaryembodiment.

The sample to be housed in the sample chamber 102 is prepared by forminga thin film, which is made of a matrix material doped with a dopingmaterial at a concentration of 12 mass %, on a quartz substrate.

The thus-obtained thin film sample is housed in the sample chamber 102,and is irradiated with a pulse laser emitted from the pulse laser 101 tobe excited. The emitted excitation light is taken in a 90-degreedirection, and is dispersed by the spectrometer 103. A two-dimensionalimage of the light is formed through the streak camera 104. In thethus-obtained two-dimensional image, an ordinate axis corresponds totime, an abscissa axis corresponds to wavelength, and a bright spotcorresponds to luminous intensity. The two-dimensional image is taken ata predetermined time axis, thereby obtaining an emission spectrum withan ordinate axis representing luminous intensity and an abscissa axisrepresenting wavelength. Further, the two-dimensional image is taken ata wavelength axis, thereby obtaining a decay curve (transient PL) withan ordinate axis representing the logarithm of luminous intensity and anabscissa axis representing time.

For instance, a thin film sample A was prepared using a referencecompound H1 below as a matrix material and a reference compound D1 belowas a doping material, and transient PL was measured.

The behavior of delayed fluorescence can be analyzed based on the decaycurve obtained by the transient PL measurement. The transient PL is aprocess where a sample is irradiated with a pulse laser to be excited,and a decay behavior (transient characteristics) of PL emission afterthe irradiation is measured. PL emission using a TADF material isdivided into an emission component from singlet excitons generated bythe first PL excitation and an emission component from singlet excitonsgenerated via triplet excitons. The lifetime of the singlet excitonsgenerated by the first PL excitation is in a nano-second order andconsiderably short. Emission from these singlet excitons thus decaysimmediately after the irradiation with the pulse laser.

In contrast, delayed fluorescence, which is emission from the singletexcitons generated via long-life triplet excitons, decays slowly. Thereis thus a large difference in time between emission from the singletexcitons generated by the first PL excitation and emission from thesinglet excitons generated via triplet excitons. Therefore, a luminousintensity resulting from the delayed fluorescence can be obtained.

Respective decay curves of the thin film sample A and a thin film sampleB were analyzed. The thin film sample B was prepared in the same manneras described above using a reference compound H2 below as a matrixmaterial and the reference compound D1 as a doping material.

FIG. 3 shows a decay curve obtained from transient PL measured usingeach of the thin film samples A and B.

As described above, an emission decay curve with an ordinate axisrepresenting luminous intensity and an abscissa axis representing timecan be obtained by the transient PL measurement. Based on the emissiondecay curve, a fluorescence intensity ratio between fluorescence emittedfrom a singlet state generated by photo-excitation and delayedfluorescence emitted from a singlet state generated by inverse energytransfer via a triplet state can be estimated. In a delayed fluorescentmaterial, a ratio of the intensity of the slowly decaying delayedfluorescence to the intensity of the promptly decaying fluorescence isrelatively large.

In the exemplary embodiment, the luminescence amount of the delayedfluorescence can be obtained using the device shown in FIG. 2 . Emissionfrom the second material includes Prompt emission and Delay emission.Prompt emission is observed immediately after the second material isbrought into an excited state, in other words, after the second materialis excited with a pulse beam (a beam emitted from a pulse laser) havinga wavelength absorbable by the second material. Delay emission isobserved not immediately after the excitation with the pulse beam butafter a while. In the exemplary embodiment, the amount of Delay emissionis preferably 5% or more relative to the amount of the Prompt emission.

The amount of Prompt emission and the amount of Delay emission can beobtained in the same method as a method described in “Nature 492,234-238, 2012 (Reference Literature 1).” The amount of Prompt emissionand the amount of Delay emission may be calculated using a devicedifferent from one described in Reference Literature 1.

Further, for measurement of delayed fluorescence, a sample prepared bythe following method is usable. For instance, a sample is prepared byco-depositing a compound TH-2 (described later) as the second materialon a quartz substrate so that the second material accounts for 12 mass %of the deposition to form a 100-nm-thick thin film.

In the exemplary embodiment, the second material preferably has a moietyrepresented by a formula (2) below and a moiety represented by a formula(2Y) below in one molecule.

In the formula (2), CN is a cyano group.

n is an integer of 1 or more. n is preferably an integer of 1 to 5, andmore preferably 2 to 4.

Z₁ to Z₆ each independently represent a nitrogen atom, a carbon atombonded to CN, or a carbon atom bonded to another atom in the molecule ofthe second material. For instance, when Z₁ is a carbon atom bonded toCN, at least one of the other five (Z₂ to Z) should be a carbon atombonded to another atom in the molecule of the second material. Theanother atom may be an atom in the moiety represented by the formula(2Y), or may be an atom in a linking group or a substituent between themoieties.

The second material of the exemplary embodiment may contain asix-membered ring including Z₁ to Z₆ as the moiety, or may contain afused ring including the six-membered ring further fused with a ring asthe moiety.

In the formula (2Y), F and G each independently represent a cyclicstructure.

m is 0 or 1.

When m is 1, Y₂₀ is a single bond, oxygen atom, sulfur atom, seleniumatom, carbon atom, silicon atom or germanium atom.

When m is 0 in the formula (2Y), the formula (2Y) is represented by aformula (20Y) below.

In the formula (20Y), a cyclic structure F and a cyclic structure G arerespectively the same as the cyclic structure F and the cyclic structureG in the formula (2Y).

When m is 1 in the formula (2Y), the formula (2Y) is represented by anyone of formulae (22) to (28) below.

In each of the formulae (22) to (28), a cyclic structure F and a cyclicstructure G are respectively the same as the cyclic structure F and thecyclic structure G in the formula (2Y).

In the exemplary embodiment, the cyclic structure F and the cyclicstructure G are each preferably a five- or six-membered ring, which ispreferably an unsaturated ring, and more preferably an unsaturatedsix-membered ring.

The second material of the exemplary embodiment is preferably a compoundrepresented by a formula (20) below.

In the formula (20), A is represented by the formula (2), in which: CNis a cyano group; n is an integer of 1 or more; Z₁ to Z₆ eachindependently represent a nitrogen atom, a carbon atom bonded to CN, acarbon atom bonded to R, a carbon atom bonded to L, or a carbon atombonded to D; at least one of Z₁ to Z₆ is the carbon atom bonded to CNand at least another one thereof is the carbon atom bonded to L or D; Reach independently represent a hydrogen atom or a substituent, thesubstituent being selected from the group consisting of a halogen atom,substituted or unsubstituted aryl group having 6 to 30 ring carbonatoms, substituted or unsubstituted aromatic heterocyclic group having 5to 30 ring atoms, substituted or unsubstituted alkyl group having 1 to30 carbon atoms, substituted or unsubstituted alkylsilyl group having 3to 30 carbon atoms, substituted or unsubstituted arylsilyl group having6 to 60 ring carbon atoms, substituted or unsubstituted alkoxy grouphaving 1 to 30 carbon atoms, substituted or unsubstituted aryloxy grouphaving 6 to 30 ring carbon atoms, substituted or unsubstitutedalkylamino group having 2 to 30 carbon atoms, substituted orunsubstituted arylamino group having 6 to 60 ring carbon atoms,substituted or unsubstituted alkylthio group having 1 to 30 carbonatoms, and substituted or unsubstituted arylthio group having 6 to 30ring carbon atoms.

In the formula (20), D is represented by the formula (2Y), in which: thecyclic structure F and the cyclic structure G may be substituted orunsubstituted; m is 0 or 1; and when m is 1, Y₂₀ is a single bond,oxygen atom, sulfur atom, selenium atom, carbonyl group, CR₂₁R₂₂,SiR₂₃R₂₄ or GeR₂₅R₂₆, and R₂₁ to R₂₆ are each the same as the groupslisted for R. When m is 1 in the formula (2Y), the formula (2Y) isrepresented by any one of the formulae (22) to (25) and formulae (21Y)to (24Y) below.

In the formula (20), (i) when L is interposed between A and D, L is asingle bond, a substituted or unsubstituted aromatic hydrocarbon grouphaving 6 to 14 ring carbon atoms, a substituted or unsubstitutedaromatic heterocyclic group having 5 to 14 ring atoms, CR₈₁R₈₂, NR₈₃, O,S, SiR₈₄R₈₅, CR₈₆R₈₇—CR₈₈R₈₉, CR₉₀═CR₉₁, a substituted or unsubstitutedaliphatic hydrocarbon ring group, or a substituted or unsubstitutedaliphatic heterocyclic group, and R₈₁ to R₉₁ each independentlyrepresent the same as R described above.

In the formula (20), (ii) when L is present at a terminal end in themolecule of the second material, L represents the same as R describedabove.

In the formula (20), f is an integer of 1 or more, e and g are eachindependently an integer of 0 or more, a plurality of A may be mutuallythe same or different, a plurality of D may be mutually the same ordifferent, and a plurality of L may be mutually the same or different.

The formula (20) is represented by, for instance, formulae (201) to(220) below.

TABLE 1 e, f and g in Formula No. Formula (20) Formula (201) e = 0, f =1, g = 0 A—L—D (202) e = 0, f = 1, g = 0 A—D (203) e = 0, f = 1, g = 1A—L—D—L—A (204) e = 0, f = 1, g = 1 A—D—A (205) e = 1, f = 1, g = 0D—L—A—L—D (206) e = 1, f = 1, g = 0 D—A—D

TABLE 2 e, f and g in Formula No. Formula (20) Formula (207) e = 1, f =1, g = 1 D—L—A—L—D—L—A (208) e = 1, f = 1, g = 1 D—A—D—A (209) e = 1, f= 2, g = 0 D—L—A—L—D—L—A—L—D (210) e = 1, f = 2, g = 0 D—A—D—A—D (211) e= 0, f = 2, g = 1 A—L—D—L—A—L—D—L—A (212) e = 0, f = 2, g = 1 A—D—A—D—A

TABLE 3 Formula e, f and g in No. Formula (20) Formula (213) e = 2, f =1, g = 0

(214) e = 2, f = 1, g = 0

(215) e = 3, f = 1, g = 0

(216) e = 3, f = 1, g = 0

TABLE 4 Formula e, f and g in No. Formula (20) Formula (217) e = 0, f =1, g = 2

(218) e = 0, f = 1, g = 2

(219) e = 0, f = 1, g = 3

(220) e = 0, f = 1, g = 3

In a bracketed repeating unit attached with a repeating unit number f inthe formula (20), D may be bonded to A via L, or A may be bonded to Avia L. For instance, the second material may have a branched structureas represented by formulae (221) to (228) below.

The second material of the exemplary embodiment is not limited to thecompounds represented by the formulae (201) to (228). It should be notedthat when L is omitted in the formulae (201) to (228), L is a singlebond between A and D, or a hydrogen atom present at a terminal end inthe molecule of the second material.

In order to keep ΔST of one molecule small, L is preferably not a fusedaromatic ring in terms of molecular design, but L may be a fusedaromatic ring as long as thermally activated delayed fluorescence isachieved. Further, since a molecular design where A and D are accuratelysituated in one molecule is required, the second material of theexemplary embodiment is preferably a low-molecule material.Specifically, the second material of the exemplary embodiment has amolecular weight of 5000 or less, and more preferably 3000 or less. Thesecond material of the exemplary embodiment preferably has the moietiesof the formulae (2) and (2Y).

The organic EL device containing the second material emits light usingthe thermally activated delayed fluorescence mechanism.

In the exemplary embodiment, the formula (2Y) is preferably representedby at least one of formulae (2a) and (2x) below.

In the formula (2x), A and B each independently represent a cyclicstructure represented by a formula (2c) below or a cyclic structurerepresented by a formula (2d) below. Each of the cyclic structure A andthe cyclic structure B is fused to an adjacent cyclic structure at anyposition. px and py are each independently an integer of 0 to 4 andrespectively represent the number of the cyclic structure A and thenumber of the cyclic structure B. When px is an integer of 2 to 4, aplurality of cyclic structures A may be mutually the same or different.When py is an integer of 2 to 4, a plurality of cyclic structures B maybe mutually the same or different. Accordingly, for instance, when px is2, the cyclic structures A may be either two cyclic structuresrepresented by the formula (2c) or two cyclic structures represented bythe formula (2d), or may alternatively be a combination of one cyclicstructure represented by the formula (2c) and one cyclic structurerepresented by the formula (2d).

In the formula (2d), Z₇ is a carbon atom, nitrogen atom, sulfur atom oroxygen atom.

When px is 0 and py is an integer of c in the formula (2x), the formula(2x) is represented by a formula (2b) below.

In the formula (2b), c is an integer of 1 to 4. When c is an integer of2 to 4, a plurality of cyclic structures E may be mutually the same ordifferent. In the formula (2b), E represents a cyclic structurerepresented by the formula (2c) or a cyclic structure represented by theformula (2d). The cyclic structure E is fused to an adjacent cyclicstructure at any position. Accordingly, for instance, when c is 2, thetwo cyclic structures E may be either two cyclic structures representedby the formula (2c) or two cyclic structures represented by the formula(2d) or may alternatively be a combination of one cyclic structurerepresented by the formula (2c) and one cyclic structure represented bythe formula (2d).

When the moieties of the formula (2) and the formula (2Y) aresimultaneously present in one molecule, the molecule can be effectivelydesigned to have a small ΔST.

The second material of the exemplary embodiment preferably has astructure represented by a formula (2e) below in the molecule.

In the formula (2e), R₁ to R₉ each independently represent a hydrogenatom, a substituent, or a single bond bonded to another atom in themolecule of the second material, the substituent being selected from thegroup consisting of a halogen atom, substituted or unsubstituted arylgroup having 6 to 30 ring carbon atoms, substituted or unsubstitutedaromatic heterocyclic group having 5 to 30 ring atoms, substituted orunsubstituted alkyl group having 1 to 30 carbon atoms, substituted orunsubstituted alkylsilyl group having 3 to 30 carbon atoms, substitutedor unsubstituted arylsilyl group having 6 to 60 ring carbon atoms,substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms,substituted or unsubstituted aryloxy group having 6 to 30 ring carbonatoms, substituted or unsubstituted alkylamino group having 2 to 30carbon atoms, substituted or unsubstituted arylamino group having 6 to60 ring carbon atoms, substituted or unsubstituted alkylthio grouphaving 1 to 30 carbon atoms, and substituted or unsubstituted arylthiogroup having 6 to 30 ring carbon atoms. It should be noted that at leastone of R₁ to R₉ is a single bond bonded to another atom in the moleculeof the second material.

In the formula (2e), at least one of combinations of substituentsselected from R₁ to R₉ may be mutually bonded to form a cyclicstructure, In other words, in the formula (2e) where R₁ to R₉ areindividually bonded to carbon atoms of the six-membered ring and R₉ isbonded to a nitrogen atom of the five-membered ring, a cyclic structuremay be formed by adjacent substituents selected from R₁ to R₈ bonded toadjacent carbon atoms and R₉ bonded to the nitrogen atom of thefive-membered ring. Specifically, in the formula (2e), at least one ofcombinations of substituents, namely, a combination of R₁ and R₂, acombination of R₂ and R₃, a combination of R₃ and R₄, a combination ofR₄ and R₅, a combination of R₅ and R₆, a combination of R₆ and R₇, acombination of R₇ and R₈, a combination of R₈ and R₉, and a combinationof R₁ and R₉, may be mutually bonded to form a cyclic structure.

In the exemplary embodiment, the cyclic structure formed by bonding thesubstituents is preferably a fused ring. For instance, in the formula(2e), the thus-formed cyclic structure may be a fused six-memberedcyclic structure.

The second material of the exemplary embodiment preferably has astructure represented by a formula (2y) below in the molecule.

R₁₁ to R₁₉ in the formula (2y) each independently represent the same asR₁ to R₉ in the formula (2e). It should be noted that at least one ofR₁₁ to R₁₉ is a single bond bonded to another atom in the molecule ofthe second material. In the formula (2y), at least one of combinationsof substituents selected from R₁₁ to R₁₉ may be mutually bonded to forma cyclic structure. In the formula (2y), A and B each independentlyrepresent a cyclic structure represented by a formula (2g) below or acyclic structure represented by a formula (2h) below. Each of the cyclicstructure A and the cyclic structure B is fused to an adjacent cyclicstructure at any position. px, which represents the number of the cyclicstructure(s) A, is an integer of 0 to 4. When px is an integer of 2 to4, a plurality of cyclic structures A may be mutually the same ordifferent. When py is an integer of 2 to 4, a plurality of cyclicstructures B may be mutually the same or different. py, which representsthe number of the cyclic structure(s) B, is an integer of 0 to 4.Accordingly, for instance, when px is 2, the two cyclic structures A maybe either two cyclic structures represented by the formula (2g) or twocyclic structures represented by the formula (2h), or may alternativelybe a combination of one cyclic structure represented by the formula (2g)and one cyclic structure represented by the formula (2h).

In the formula (2g), R₂₀₁ and R₂₀₂ each independently represent the sameas R₁ to R₉ described above and may be mutually bonded to form a cyclicstructure. R₂₀₁ and R₂₀₂ are individually bonded to carbon atoms formingthe six-membered ring of the formula (2g).

In the formula (2h), Z₈ represents CR₂₀₃R₂₀₄, NR₂₀₅, a sulfur atom, oran oxygen atom, and R₂₀₂ to R₂₀₅ each independently represent the sameas the substituents for R₁ to 15 R₉ described above.

In the formula (2y), at least one of combinations of substituentsselected from R₁₁ to R₁₉ and R₂₀₁ to R₂₀₅ may be mutually bonded to forma cyclic structure.

When px is 0 and py is an integer of c in the formula (2y), the formula(2y) is represented by a formula (2f) below.

R₁₁ to R₁₉ in the formula (2f) each independently represent the same asR₁ to R₉ in the formula (2e). It should be noted that at least one ofR₁₁ to R₁₉ is a single bond bonded to another atom in the molecule ofthe second material. In the formula (2f), at least one of combinationsof substituents selected from R₁₁ to R₁₉ may be mutually bonded to forma cyclic structure. In the formula (2f), E represents a cyclic structurerepresented by the formula (2g) or a cyclic structure represented by theformula (2h). The cyclic structure E is fused to an adjacent cyclicstructure at any position. c, which represents the number of the cyclicstructure(s) E, is an integer of 1 to 4. When c is an integer of 2 to 4,a plurality of cyclic structures E may be mutually the same ordifferent. Accordingly, for instance, when c is 2, the two cyclicstructures E may be either two cyclic structures represented by theformula (2g) or two cyclic structures represented by the formula (2h),or may alternatively be a combination of one cyclic structurerepresented by the formula (2g) and one cyclic structure represented bythe formula (2h).

The second material of the exemplary embodiment is preferablyrepresented by a formula (2A) below.

In the formula (2A), n is an integer of 1 or more, t is an integer of 1or more, and u is an integer of 0 or more. L_(A) is a substituted orunsubstituted aromatic hydrocarbon ring having 6 to 30 ring carbon atomsor aromatic heterocycle having 6 to 30 ring atoms. CN is a cyano group.D₁ and D₂ are each independently represented by the formula (2Y), inwhich: the cyclic structure F and the cyclic structure G may besubstituted or unsubstituted; m is 0 or 1; and when m is 1, Y₂₀ is asingle bond, oxygen atom, sulfur atom, selenium atom, carbonyl group,CR₂₁R₂₂, SiR₂₃R₂₄ or GeR₂₅R₂₆, and R₂₁ to R₂₆ are each the same as Rdescribed above. When m is 1, the formula (2Y) is represented by any oneof the formulae (22) to (25) and the formulae (21Y) to (24Y). D₁ and D₂may be mutually the same or different. When t is 2 or more, a pluralityof D₁ may be mutually the same or different. When u is 2 or more, aplurality of D₂ may be mutually the same or different.

In the exemplary embodiment, L_(A) is preferably a substituted orunsubstituted aromatic hydrocarbon ring having 6 to 14 ring carbonatoms. Examples of the aromatic hydrocarbon ring having 6 to 14 ringcarbon atoms include benzene, naphthalene, fluorene and phenanthrene.L_(A) is further preferably an aromatic hydrocarbon ring having 6 to 10ring carbon atoms.

Examples of the aromatic heterocycle having 6 to 30 ring atoms for L_(A)include pyridine, pyrimidine, pyrazine, quinoline, quinazoline,phenanthroline, benzofuran and dibenzofuran.

In the exemplary embodiment, in the formula (2A), D₁ or D₂ may be bondedto a first one of the carbon atoms forming the aromatic hydrocarbon ringrepresented by L_(A), and CN may be bonded to a second one adjacent tothe first one. For instance, in the second material of the exemplaryembodiment, D may be bonded to a first carbon atom C₁, and a cyano groupmay be bonded to a second carbon atom C2 adjacent to the first carbonatom C₁ as shown in a moiety represented by a formula (2B) below. D inthe formula (2B) represents the same as D₁ or D₂. In the formula (2B), awavy line(s) shows a bonding position with another structure or an atom.

When D₁ or D₂ having a structure represented by the formula (2a) or (2b)and the cyano group are adjacently bonded to the aromatic hydrocarbonring represented by L_(A), a value of ΔST of the compound can bereduced.

In the exemplary embodiment, t is preferably an integer of 2 or more.When 2 or more D₁ are bonded to the aromatic hydrocarbon ringrepresented by L_(A), a plurality of D₁ may be the same or different instructure.

The second material of the exemplary embodiment is preferablyrepresented by a formula (21) below.

In the formula (21), A₂₁ and B₂₁ each independently represent asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms or a substituted or unsubstituted aromaticheterocyclic having 5 to 30 ring atoms.

X₂₁ to X₂₈ and Y₂₁ to Y₂₈ each independently represent a nitrogen atom,a carbon atom bonded to R^(D), or a carbon atom bonded to L₂₃. It shouldbe noted that at least one of X_(2S) to X₂₈ is a carbon atom bonded toL₂₃, and at least one of Y₂₁ to Y₂₄ is a carbon atom bonded to L₂₃.

R^(D) each independently represent a hydrogen atom or a substituent, thesubstituent being selected from the group consisting of a halogen atom,substituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, substituted or unsubstituted aromatic heterocyclicgroup having 5 to 30 ring atoms, substituted or unsubstituted alkylgroup having 1 to 30 carbon atoms, and substituted or unsubstitutedsilyl group.

L₂₁ and L₂ each independently represent a single bond or a linkinggroup. The linking group for L₂₁ and L₂₂ is any one of a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms, substituted or unsubstituted heterocyclic group having 5 to 30ring atoms, multiple linking group including 2 to 4 groups selected fromthe above aromatic hydrocarbon groups, multiple linking group includingbonded 2 to 4 groups selected from the above heterocyclic groups, andmultiple linking group including bonded 2 to 4 groups selected from theabove aromatic hydrocarbon groups and heterocyclic groups.

L₂₃ represents a substituted or unsubstituted monocyclic hydrocarbongroup having 6 or less ring carbon atoms or a substituted orunsubstituted monocyclic heterocyclic group having 6 or less ring atoms.

w is an integer of 0 to 3. When w is 0, at least one of X₂₅ to X₂₈ andat least one of Y₂₁ to Y₂₄ are directly bonded.

It should be noted that the monocyclic hydrocarbon group is not a fusedring but a group derived from a single hydrocarbon ring (aliphaticcyclic hydrocarbon or aromatic hydrocarbon), and the monocyclicheterocyclic group is a group derived from a single heterocycle.

Further, the formula (21) satisfies at least one of the followingconditions (i) and (ii): (i) at least one of A₂₁ and B₂₁ is acyano-substituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms or a cyano-substituted aromatic heterocyclic group having 6 to 30ring atoms; and (i) at least one of X₂₁ to X₂₄ and Y₂₅ to Y₂₈ is acarbon atom bonded to R^(D), and at least one of R^(D) is acyano-substituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms or a cyano-substituted aromatic heterocyclic group having 6 to 30ring atoms.

It should be noted that a plurality of R^(D) may be mutually the same ordifferent.

In the formula (21), when the aromatic hydrocarbon group having 6 to 30ring carbon atoms or the aromatic heterocyclic group having 6 to 30 ringatoms represented by A₂₁ and B₂₁ is substituted, the substituent ispreferably at least one group selected from the group consisting of acyano group, halogen atom, alkyl group having 1 to 20 carbon atoms,cycloalkyl group having 3 to 20 carbon atoms, alkoxy group having 1 to20 carbon atoms, haloalkyl group having 1 to 20 carbon atoms, haloalkoxygroup having 1 to 20 carbon atoms, alkylsilyl group having 1 to 10carbon atoms, aryl group having 6 to 30 ring carbon atoms, aryloxy grouphaving 6 to 30 ring carbon atoms, aralkyl group having 6 to 30 carbonatoms, and heterocyclic group having 5 to 30 ring atoms. When A₂₁ andB₂₁ have a plurality of substituents, the substituents may be mutuallythe same or different.

The formula (21) preferably satisfies the condition (i) but not thecondition (ii).

Alternatively, the formula (21) preferably satisfies the condition (ii)but not the condition (i).

Further, the formula (21) preferably satisfies the conditions (i) and(ii).

In the formula (21), at least one of A₂₁ and B₂₁ is preferably any oneof a cyano-substituted phenyl group, a cyano-substituted naphthyl group,a cyano-substituted phenanthryl group, a cyano-substituteddibenzofuranyl group, a cyano-substituted dibenzothiophenyl group, acyano-substituted biphenyl group, a cyano-substituted terphenyl group, acyano-substituted 9,9-diphenylfluorenyl group, a cyano-substituted9,9′-spirobi[9H-fluorene]-2-yl group, a cyano-substituted9,9-dimethylfluorenyl group, and a cyano-substituted triphenylenylgroup.

In the formula (21), at least one of X₂₁ to X₂₄ and Y₂₅ to Y₂₈ isCR^(D), and at least one of R^(D) for X₂₁ to X₂₄ and Y₂₅ to Y₂₈ ispreferably any one of a cyano-substituted phenyl group, acyano-substituted naphthyl group, a cyano-substituted phenanthryl group,a cyano-substituted dibenzofuranyl group, a cyano-substituteddibenzothiophenyl group, a cyano-substituted biphenyl group, acyano-substituted terphenyl group, a cyano-substituted9,9-diphenylfluorenyl group, a cyano-substituted9,9′-spirobi[9H-fluorene]-2-yl group, a cyano-substituted9,9-dimethylfluorenyl group, and a cyano-substituted triphenylenylgroup.

In the formula (21), X₆ and Y₂₃ are preferably bonded to each other viaL₂₃ or directly bonded to each other.

In the formula (21), X₂₆ and Y₂₂ are preferably bonded to each other viaL₂₃ or directly bonded to each other.

In the formula (21), X₂₇ and Y₂₃ are preferably bonded to each other viaL₂₃ or directly bonded to each other.

In the general formula (21), w is preferably 0.

Alternatively, in the general formula (21), w is preferably 1.

In the formula (21), L₂₁ and L₂ each represent a single bond or asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms.

Specific examples of the second material of the exemplary embodiment areshown below. It should be noted that the second material according tothe invention may be different from these specific examples.

Method of Preparing Second Material

The second material may be prepared by reacting a commercially availablecompound having the moiety represented by the formula (2), in which atleast one of Z₁ to Z₆ is a carbon atom bonded to a halogen atom, with acompound represented by the formula (2Y), in which a hydrogen atom isbonded to a nitrogen atom bonded to the cyclic structures F and G, underthe presence of a catalyst such as tetrakis(triphenylphosphine)palladiumand base.

Third Material

The third material of the exemplary embodiment has a singlet energylarger than that of the second material.

In the exemplary embodiment, the third material preferably has at leastone of a moiety represented by a formula (31) below and a moietyrepresented by a formula (32) below in one molecule.

In the formula (31), X₃₁ to X₃₆ each independently represent a nitrogenatom, or a carbon atom bonded to another atom in the molecule of thethird material, and at least one of X₃₁ to X₃₆ is the carbon atom bondedto another atom in the molecule of the third material.

In the formula (32), Y₃₁ to Y₃₈ each independently represent a nitrogenatom, or a carbon atom bonded to another atom in the molecule of thethird material, at least one of Y₃₁ to Y₃₈ is the carbon atom bonded toanother atom in the molecule of the third material, and Y₃₉ represents anitrogen atom, oxygen atom or sulfur atom.

In the exemplary embodiment, the moiety represented by the formula (31)is preferably in the form of at least one group selected from the groupconsisting of formulae (33) and (34) below and contained in the thirdmaterial.

For the third material, bonding positions are preferably both situatedin meta positions as shown in the formulae (33) and (34) to keep anenergy gap Eg_(77K)(M3) at 77 [K] high.

In the formulae (33) and (34), X₃₁, X₃₂, X₃₄ and X₃₆ each independentlyrepresent a nitrogen atom or CR₃₁, R₃₁ being a hydrogen atom or asubstituent, the substituent being selected from the group consisting ofa halogen atom, a cyano group, a substituted or unsubstituted alkylgroup having 1 to 30 carbon atoms, a substituted or unsubstitutedcycloalkyl group having 3 to 30 ring carbon atoms, a substituted orunsubstituted trialkylsilyl group, a substituted or unsubstitutedarylalkylsilyl group, a substituted or unsubstituted triarylsilyl group,a substituted or unsubstituted diaryl phosphine oxide group, asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, and a substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, the substituted or unsubstituted aromatichydrocarbon group having 6 to 30 ring carbon atoms being a non-fusedring.

In the formulae (33) and (34), a wavy line(s) shows a bonding positionwith another atom or another structure in the molecule of the thirdmaterial.

In the exemplary embodiment, R₃₁ is preferably a hydrogen atom or asubstituent, the substituent being selected from the group consisting ofa halogen atom, cyano group, substituted or unsubstituted alkyl grouphaving 1 to 30 carbon atoms, substituted or unsubstituted aromatichydrocarbon group having 6 to 30 ring carbon atoms, and substituted orunsubstituted heterocyclic group having 5 to 30 ring atoms. R₃₁ is morepreferably a hydrogen atom, cyano group, substituted or unsubstitutedaromatic hydrocarbon group having 6 to 30 ring carbon atoms, orsubstituted or unsubstituted heterocyclic group having 5 to 30 ringatoms.

In the exemplary embodiment, X₃₁, X₃₂, X₃₄ and X₃₆ in the formula (33)each independently represent CR₃₁.

In the exemplary embodiment, X₃₂, X₃₄ and X₃₆ in the formula (34) eachindependently represent CR₃₁.

In the exemplary embodiment, the moiety represented by the formula (32)is preferably in the form of at least one group selected from the groupconsisting of formulae (35), (36), (37), (38), (39) and (30a) below andcontained in the third material.

For the third material, bonding positions are preferably situated asshown in the formulae (35), (36), (37), (38), (39) and (30a) to keep theenergy gap Eg_(77K) at 77 [K] high.

In the formulae (35) to (39) and (30a), Y₃₁ to Y₃₈ each independentlyrepresent a nitrogen atom or CR₃₂, R₃₂ being a hydrogen atom or asubstituent, the substituent being selected from the group consisting ofa halogen atom, a cyano group, a substituted or unsubstituted alkylgroup having 1 to 30 carbon atoms, a substituted or unsubstitutedcycloalkyl group having 3 to 30 ring carbon atoms, a substituted orunsubstituted trialkylsilyl group, a substituted or unsubstitutedarylalkylsilyl group, a substituted or unsubstituted triarylsilyl group,a substituted or unsubstituted diaryl phosphine oxide group, asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, and a substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, the substituted or unsubstituted aromatichydrocarbon group having 6 to 30 ring carbon atoms being a non-fusedring.

In the formulae (35) and (36), Y₃₉ represents a nitrogen atom.

In the formulae (37) to (39) and (30a), Y₃₉ represents NR₃₃, an oxygenatom or a sulfur atom, R₃₃ being a substituent that is selected from thegroup consisting of a cyano group, a substituted or unsubstituted alkylgroup having 1 to 20 carbon atoms, a substituted or unsubstitutedcycloalkyl group having 3 to 20 ring carbon atoms, a substituted orunsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted orunsubstituted aryloxy group having 6 to 30 ring carbon atoms, asubstituted or unsubstituted alkylthio group having 1 to 20 carbonatoms, a substituted or unsubstituted arylthio group having 6 to 30 ringcarbon atoms, a substituted or unsubstituted alkylsilyl group having 3to 50 carbon atoms, a substituted or unsubstituted arylsilyl grouphaving 6 to 50 ring carbon atoms, a substituted or unsubstituted arylgroup having 6 to 30 ring carbon atoms, and a substituted orunsubstituted heterocyclic group having 5 to 30 ring atoms, thesubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms being a non-fused ring.

In the formulae (35) to (39) and (30a), a wavy line(s) shows a bondingposition with another atom or another structure in the molecule of thethird material.

In the exemplary embodiment, R₃₂ is preferably a hydrogen atom or asubstituent, the substituent being selected from the group consisting ofa halogen atom, cyano group, substituted or unsubstituted alkyl grouphaving 1 to 30 carbon atoms, substituted or unsubstituted aromatichydrocarbon group having 6 to 30 ring carbon atoms, and substituted orunsubstituted heterocyclic group having 5 to 30 ring atoms. R₃₂ is morepreferably a hydrogen atom or a substituted or unsubstituted alkyl grouphaving 1 to 30 carbon atoms.

In the exemplary embodiment, Y₃₁ to Y₃₈ in the formula (35) eachindependently represent CR₃₂.

In the formulae (36) and (37), Y₃₁ to Y₃₅, Y₃₇ and Y₃₈ preferably eachindependently represent CR₃₂.

In the formula (38), Y₃₁, Y₃₂, Y₃, Y₃₅, Y₃₇ and Y₃₈ preferably eachindependently represent CR₃₂.

In the formula (39), Y₃₂ to Y₃₈ preferably each independently representCR₃₂.

In the formula (30a), Y₃₂ to Y₃₇ preferably each independently representCR₃₂.

In the above case, a plurality of R₃₂ may be mutually the same ordifferent.

In the exemplary embodiment, the third material preferably contains agroup represented by a formula (30b) below.

For the third material, a bonding position is preferably situated asshown in the formula (30b) to keep the energy gap Eg_(77K) at 77 [K]high.

In the formula (30b): X₃₁, X₃₂, X₃₄ and X₃₆ each independently representa nitrogen atom or CR₃₁; Y₃₁, Y₃₂ and Y₃₄ to Y₃₈ each independentlyrepresent a nitrogen atom, CR₃₂ or a carbon atom bonded to another atomin the molecule of the third material; R₃₁ and R₃₂ each independentlyrepresent a hydrogen atom or a substituent, the substituent beingselected from the group consisting of a halogen atom, cyano group,substituted or unsubstituted alkyl group having 1 to 30 carbon atoms,substituted or unsubstituted cycloalkyl group having 3 to 30 ring carbonatoms, substituted or unsubstituted trialkylsilyl group, substituted orunsubstituted arylalkylsilyl group, substituted or unsubstitutedtriarylsilyl group, substituted or unsubstituted diaryl phosphine oxidegroup, substituted or unsubstituted aromatic hydrocarbon group having 6to 30 ring carbon atoms, and substituted or unsubstituted heterocyclicgroup having 5 to 30 ring atoms, the substituted or unsubstitutedaromatic hydrocarbon group having 6 to 30 ring carbon atoms being anon-fused ring; Y₃₉ represents NR₃₃, an oxygen atom or a sulfur atom,R₃₃ being a substituent that is selected from the group consisting of acyano group, substituted or unsubstituted alkyl group having 1 to 20carbon atoms, substituted or unsubstituted cycloalkyl group having 3 to20 ring carbon atoms, substituted or unsubstituted alkoxy group having 1to 20 carbon atoms, substituted or unsubstituted aryloxy group having 6to 30 ring carbon atoms, substituted or unsubstituted alkylthio grouphaving 1 to 20 carbon atoms, substituted or unsubstituted arylthio grouphaving 6 to 30 ring carbon atoms, substituted or unsubstitutedalkylsilyl group having 3 to 50 carbon atoms, substituted orunsubstituted arylsilyl group having 6 to 50 ring carbon atoms,substituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, and substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, the substituted or unsubstituted aromatichydrocarbon group having 6 to 30 ring carbon atoms being a non-fusedring; X₃₂ and Y₃₄ may be cross-linked via an oxygen atom, sulfur atom orCR₅₁R₅₂; X₃₄ and Y₃₂ may be cross-linked via an oxygen atom, sulfur atomor CR₅₃R₅₄; and R₅₁ to R₅₄ each independently represent the same as R₃₃being the substituent.

In the formula (30b), a wavy line(s) shows a bonding position withanother atom or another structure in the molecule of the third material.

For instance, when X₃₂ and Y₃₄ are cross-linked via an oxygen atom,sulfur atom or CR₅₁R₅₂ in the formula (30b), the formula (30b) isrepresented by a formula (30b-1) below.

It should be noted that Z₃₁ is an oxygen atom, sulfur atom or CR₅₁R₅₂ inthe formula (30b-1).

In the exemplary embodiment, the third material preferably contains agroup represented by a formula (30c) below.

For the third material, a bonding position is preferably situated asshown in the formula (30c) to keep the energy gap Eg_(77K) at 77 [K]high.

In the formula (30c): X₃₁, X₃₂, X₃₄ and X₃₆ each independently representa nitrogen atom or CR₃₁; Y₃₁, Y₃₂, Y₃₄, Y₃₅, Y₃₇ and Y₃₈ eachindependently represent a nitrogen atom or CR₃₂; Y₄₁ to Y₄₅, Y₄₇ and Y₄₈each independently represent a nitrogen atom, CR₃₄ or a carbon atombonded to another atom in the molecule of the third material; R₃₁, R₃₂and R₃₄ each independently represent a hydrogen atom or a substituent,the substituent being selected from the group consisting of a halogenatom, cyano group, substituted or unsubstituted alkyl group having 1 to30 carbon atoms, substituted or unsubstituted cycloalkyl group having 3to 30 ring carbon atoms, substituted or unsubstituted trialkylsilylgroup, substituted or unsubstituted arylalkylsilyl group, substituted orunsubstituted triarylsilyl group, substituted or unsubstituted diarylphosphine oxide group, substituted or unsubstituted aromatic hydrocarbongroup having 6 to 30 ring carbon atoms, and substituted or unsubstitutedheterocyclic group having 5 to 30 ring atoms, the substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms being a non-fused ring; Y₃₉ represents NR₃₃, an oxygen atom or asulfur atom; Y₄₉ represents NR₃₅, an oxygen atom or a sulfur atom; R₃₃and R₃₅ each independently represent a substituent that is selected fromthe group consisting of a cyano group, substituted or unsubstitutedalkyl group having 1 to 20 carbon atoms, substituted or unsubstitutedcycloalkyl group having 3 to 20 ring carbon atoms, substituted orunsubstituted alkoxy group having 1 to 20 carbon atoms, substituted orunsubstituted aryloxy group having 6 to 30 ring carbon atoms,substituted or unsubstituted alkylthio group having 1 to 20 carbonatoms, substituted or unsubstituted arylthio group having 6 to 30 ringcarbon atoms, substituted or unsubstituted alkylsilyl group having 3 to50 carbon atoms, substituted or unsubstituted arylsilyl group having 6to 50 ring carbon atoms, substituted or unsubstituted aromatichydrocarbon group having 6 to 30 ring carbon atoms, and substituted orunsubstituted heterocyclic group having 5 to 30 ring atoms, thesubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms being a non-fused ring; X₃₂ and Y₃₄ may becross-linked via an oxygen atom, sulfur atom or CR₅₁R₅₂; X₃₄ and Y₃₂ maybe cross-linked via an oxygen atom, sulfur atom or CR₅₃R₅₄; and R₅₁ toR₅₄ each independently represent the same as R₃₃ and R₃₅ each being thesubstituent.

In the formula (30c), a wavy line(s) shows a bonding position withanother atom or another structure in the molecule of the third material.

For instance, when X₃₂ and Y₃₄ are cross-linked via an oxygen atom,sulfur atom or CR₅₁R₅₂ in the formula (30c), the formula (30c) isrepresented by a formula (30c-1) below.

It should be noted that Z₃₂ is an oxygen atom, sulfur atom or CR₅₁R₅₂ inthe formula (30c-1).

In the exemplary embodiment, the third material preferably contains agroup represented by a formula (30d) below.

For the third material, bonding positions are preferably situated asshown in the formula (30d) to keep the energy gap Eg_(77K) at 77 [K]high.

In the formula (30d): X₃₁, X₃₂, X₃₄ and X₆ each independently representa nitrogen atom or CR₃₁; X₄₁, X₄₃, X₄₄ and X₄₃ each independentlyrepresent a nitrogen atom or CR₃₆; R₃₁ and R₆ each independentlyrepresent a substituent that is selected from the group consisting of ahalogen atom, cyano group, substituted or unsubstituted alkyl grouphaving 1 to 30 carbon atoms, substituted or unsubstituted cycloalkylgroup having 3 to 30 ring carbon atoms, substituted or unsubstitutedtrialkylsilyl group, substituted or unsubstituted arylalkylsilyl group,substituted or unsubstituted triarylsilyl group, substituted orunsubstituted diaryl phosphine oxide group, substituted or unsubstitutedaromatic hydrocarbon group having 6 to 30 ring carbon atoms, andsubstituted or unsubstituted heterocyclic group having 5 to 30 ringatoms, the substituted or unsubstituted aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms being a non-fused ring; X₃₂ and X₄₁ maybe cross-linked via an oxygen atom, sulfur atom or CR₅₅R₅₆; X₃₄ and X₄₅may be cross-linked via an oxygen atom, sulfur atom or CR₅₇R₅₈; and R₅₅to R₅₈ each independently represent a substituent that is selected fromthe group consisting of a halogen atom, cyano group, substituted orunsubstituted alkyl group having 1 to 20 carbon atoms, substituted orunsubstituted cycloalkyl group having 3 to 20 ring carbon atoms,substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms,substituted or unsubstituted aryloxy group having 6 to 30 ring carbonatoms, substituted or unsubstituted alkylthio group having 1 to 20carbon atoms, substituted or unsubstituted arylthio group having 6 to 30ring carbon atoms, substituted or unsubstituted alkylsilyl group having3 to 50 carbon atoms, substituted or unsubstituted arylsilyl grouphaving 6 to 50 ring carbon atoms, substituted or unsubstituted aromatichydrocarbon group having 6 to 30 ring carbon atoms, and substituted orunsubstituted heterocyclic group having 5 to 30 ring atoms, thesubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms being a non-fused ring.

In the formula (30d), a wavy line(s) shows a bonding position withanother atom or another structure in the molecule of the third material.

For instance, when X₃₂ and X₄₁ are cross-linked via an oxygen atom,sulfur atom or CR₅₅R₅₆ in the formula (30d), the formula (30d) isrepresented by a formula (30d-1) below.

It should be noted that Z₃₃ is an oxygen atom, sulfur atom or CR₅₅R₅₆ inthe formula (30d-1).

In the exemplary embodiment, the third material preferably contains agroup represented by a formula (30e) below.

For the third material, a bonding position is preferably situated asshown in the formula (30e) to keep the energy gap Eg_(77K) at 77 [K]high.

In the formula (30e): X₃₁, X₃₂, X₃₄ and X₃₆ each independently representa nitrogen atom or CR₃₁; X₄₁, X₄₃, X₄₄ and X₄₅ each independentlyrepresent a nitrogen atom or CR₃₆; Y₃₁ to Y₃₅, Y₃₇ and Y₃₈ eachindependently represent a nitrogen atom, CR₃₂ or a carbon atom bonded toanother atom in the molecule of the third material; R₃₁, R₃₂ and R₃₆each independently represent a hydrogen atom or a substituent, thesubstituent being selected from the group consisting of a halogen atom,cyano group, substituted or unsubstituted alkyl group having 1 to 30carbon atoms, substituted or unsubstituted cycloalkyl group having 3 to30 ring carbon atoms, substituted or unsubstituted trialkylsilyl group,substituted or unsubstituted arylalkylsilyl group, substituted orunsubstituted triarylsilyl group, substituted or unsubstituted diarylphosphine oxide group, substituted or unsubstituted aromatic hydrocarbongroup having 6 to 30 ring carbon atoms, and substituted or unsubstitutedheterocyclic group having 5 to 30 ring atoms, the substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms being a non-fused ring; Y₃₉ represents NR₃₃, an oxygen atom or asulfur atom, R₃₃ being a substituent that is selected from the groupconsisting of a cyano group, substituted or unsubstituted alkyl grouphaving 1 to 20 carbon atoms, substituted or unsubstituted cycloalkylgroup having 3 to 20 ring carbon atoms, substituted or unsubstitutedalkoxy group having 1 to 20 carbon atoms, substituted or unsubstitutedaryloxy group having 6 to 30 ring carbon atoms, substituted orunsubstituted alkylthio group having 1 to 20 carbon atoms, substitutedor unsubstituted arylthio group having 6 to 30 ring carbon atoms,substituted or unsubstituted alkylsilyl group having 3 to 50 carbonatoms, substituted or unsubstituted arylsilyl group having 6 to 50 ringcarbon atoms, substituted or unsubstituted aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms, and substituted or unsubstitutedheterocyclic group having 5 to 30 ring atoms, the substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms being a non-fused ring; X₃₂ and X₄ may be cross-linked via anoxygen atom, sulfur atom or CR₅₅R₅₆; X₃₄ and X₄₅ may be cross-linked viaan oxygen atom, sulfur atom or CR₅₇R₅₈; X₄₁ and Y₃₇ may be cross-linkedvia an oxygen atom, sulfur atom or CR₅₉R₆₀; X₄₃ and Y₃₅ may becross-linked via an oxygen atom, sulfur atom or CR₆₁R₆₂; and R₅₅ to R₆₂each independently represent the same as R₃₃ being the substituent.

In the formula (30e), a wavy line(s) shows a bonding position withanother atom or another structure in the molecule of the third material.

For instance, when X₃₂ and X₄₁ are cross-linked via an oxygen atom,sulfur atom or CR₅₅R₆ in the formula (30e), the formula (30e) isrepresented by a formula (30e-1) below.

It should be noted that Z₃₄ is an oxygen atom, sulfur atom or CR₅₅R₅₆ inthe formula (30e-1).

For instance, when X₁ and Y₃₇ are cross-linked via an oxygen atom,sulfur atom or CR₅₉R₆₀ in the formula (30e), the formula (30e) isrepresented by a formula (30e-2) below.

It should be noted that Z₃₅ is an oxygen atom, sulfur atom or CR₅₅R₅₆,in the formula (30e-2).

In the exemplary embodiment, the third material preferably contains agroup represented by a formula (30f) below.

For the third material, a bonding position is preferably situated asshown in the formula (30f) to keep the energy gap Eg_(77K) at 77 [K]high.

In the formula (30f): Y₃₁, Y₃₂, Y₃₄, Y₃₅, Y₃₇ and Y₃₈ each independentlyrepresent a nitrogen atom or CR₃₂; Y₄₁ to Y₄₅, Y₄₇ and Y₄₈ eachindependently represent a nitrogen atom, CR₃₄ or a carbon atom bonded toanother atom in the molecule of the third material; R₃₂ and R₃₄ eachindependently represent a hydrogen atom or a substituent, thesubstituent being selected from the group consisting of a halogen atom,cyano group, substituted or unsubstituted alkyl group having 1 to 30carbon atoms, substituted or unsubstituted cycloalkyl group having 3 to30 ring carbon atoms, substituted or unsubstituted trialkylsilyl group,substituted or unsubstituted arylalkylsilyl group, substituted orunsubstituted triarylsilyl group, substituted or unsubstituted diarylphosphine oxide group, substituted or unsubstituted aromatic hydrocarbongroup having 6 to 30 ring carbon atoms, and substituted or unsubstitutedheterocyclic group having 5 to 30 ring atoms, the substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms being a non-fused ring; Y₃₉ represents NR₃₃, an oxygen atom or asulfur atom; Y₄₉ represents NR₃₃, an oxygen atom or a sulfur atom; andR₃₃ and R₃₅ each independently represent a hydrogen atom or asubstituent, the substituent being selected from the group consisting ofa cyano group, substituted or unsubstituted alkyl group having 1 to 20carbon atoms, substituted or unsubstituted cycloalkyl group having 3 to20 ring carbon atoms, substituted or unsubstituted alkoxy group having 1to 20 carbon atoms, substituted or unsubstituted aryloxy group having 6to 30 ring carbon atoms, substituted or unsubstituted alkylthio grouphaving 1 to 20 carbon atoms, substituted or unsubstituted arylthio grouphaving 6 to 30 ring carbon atoms, substituted or unsubstitutedalkylsilyl group having 3 to 50 carbon atoms, substituted orunsubstituted arylsilyl group having 6 to 50 ring carbon atoms,substituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, and substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, the substituted or unsubstituted aromatichydrocarbon group having 6 to 30 ring carbon atoms being a non-fusedring.

In the formula (30f), a wavy line(s) shows a bonding position withanother atom or another structure in the molecule of the third material.

In the exemplary embodiment, the third material may contain at least oneof groups represented by formulae (30g), (30h) and (30i) below.

In the formulae (30g), (30h) and (30i): Y₃₁ to Y₃₈, Y₄₁ to Y₄₈ and Y₅₁to Y₅₈ each independently represent a nitrogen atom, CR₃₇ or a carbonatom bonded to another atom in the molecule of the third material; R₃₇each independently represent a hydrogen atom or a substituent, thesubstituent being selected from the group consisting of a halogen atom,cyano group, substituted or unsubstituted alkyl group having 1 to 30carbon atoms, substituted or unsubstituted cycloalkyl group having 3 to30 ring carbon atoms, substituted or unsubstituted trialkylsilyl group,substituted or unsubstituted arylalkylsilyl group, substituted orunsubstituted triarylsilyl group, substituted or unsubstituted diarylphosphine oxide group, substituted or unsubstituted aromatic hydrocarbongroup having 6 to 30 ring carbon atoms, and substituted or unsubstitutedheterocyclic group having 5 to 30 ring atoms, the substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms being a non-fused ring; and Y₄₉ and Y₅₉ each independentlyrepresent NR₃₈, an oxygen atom or a sulfur atom, R₃₈ being eachindependently a hydrogen atom or a substituent, the substituent beingselected from the group consisting of a halogen atom, cyano group,substituted or unsubstituted alkyl group having 1 to 20 carbon atoms,substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbonatoms, substituted or unsubstituted alkoxy group having 1 to 20 carbonatoms, substituted or unsubstituted aryloxy group having 6 to 30 ringcarbon atoms, substituted or unsubstituted alkylthio group having 1 to20 carbon atoms, substituted or unsubstituted arylthio group having 6 to30 ring carbon atoms, substituted or unsubstituted alkylsilyl grouphaving 3 to 50 carbon atoms, substituted or unsubstituted arylsilylgroup having 6 to 50 ring carbon atoms, substituted or unsubstitutedaromatic hydrocarbon group having 6 to 30 ring carbon atoms, andsubstituted or unsubstituted heterocyclic group having 5 to 30 ringatoms, the substituted or unsubstituted aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms being a non-fused ring.

In the formulae (30g), (30h) and (30i), a wavy line(s) shows a bondingposition with another atom or another structure in the molecule of thethird material.

In the formulae (32), (35), (36), (37), (38), (39), (30a), (30b), (30c),(30e), (30f), (30h) and (30i), when Y₃₉ and Y₄₉ are each independentlyan oxygen atom or a sulfur atom, an ionization potential Ip isincreased, which is preferable for the third material. When Y₃₉ and Y₄₉are each an oxygen atom, the ionization potential Ip is furtherincreased, which is further preferable.

In the exemplary embodiment, the third material is also preferably anaromatic hydrocarbon compound or an aromatic heterocyclic compound.

Method of Preparing Third Material

The third material represented by the formula may be prepared by amethod described in WO2012/153780 A1 or WO 2013/038650 A1.

Specific examples of the substituent for the third material of theexemplary embodiment are shown below, but the invention is not limitedthereto.

Specific examples of the aromatic hydrocarbon group (aryl group) includea phenyl group, tolyl group, xylyl group, naphthyl group, phenanthrylgroup, pyrenyl group, chrysenyl group, benzo[c]phenanthryl group,benzo[g]chrysenyl group, benzoanthryl group, triphenylenyl group,fluorenyl group, 9,9-dimethylfluorenyl group, benzofluorenyl group,dibenzofluorenyl group, biphenyl group, terphenyl group, quarterphenylgroup and fluoranthenyl group, among which a phenyl group, biphenylgroup, terphenyl group, quarterphenyl group, naphthyl group,triphenylenyl group and fluorenyl group may be preferable.

Specific examples of the substituted aromatic hydrocarbon group includea tolyl group, xylyl group and 9,9-dimethylfluorenyl group.

As is understood from the specific examples, the aryl group includesboth fused aryl group and non-fused aryl group.

Preferable examples of the aromatic hydrocarbon group include a phenylgroup, biphenyl group, terphenyl group, quarterphenyl group, naphthylgroup, triphenylenyl group and fluorenyl group.

For an organic EL device including a blue-emitting layer, the aromatichydrocarbon group as a substituent in the third material is preferably anon-fused aromatic hydrocarbon group.

Specific examples of the aromatic heterocyclic group (heteroaryl group,heteroaromatic ring group and heterocyclic group) include a pyrrolylgroup, pyrazolyl group, pyrazinyl group, pyrimidinyl group, pyridazynylgroup, pyridyl group, triazinyl group, indolyl group, isoindolyl group,imidazolyl group, benzimidazolyl group, indazolyl group,imidazo[1,2-a]pyridinyl group, furyl group, benzofuranyl group,isobenzofuranyl group, dibenzofuranyl group, azadibenzofuranyl group,thiophenyl group, benzothiophenyl group, dibenzothiophenyl group,azadibenzothiophenyl group, quinolyl group, isoquinolyl group,quinoxalinyl group, quinazolinyl group, naphthyridinyl group, carbazolylgroup, azacarbazolyl group, phenanthridinyl group, acridinyl group,phenanthrolinyl group, phenazinyl group, phenothiazinyl group,phenoxazinyl group, oxazolyl group, oxadiazolyl group, furazanyl group,benzoxazolyl group, thienyl group, thiazolyl group, thiadiazolyl group,benzothiazolyl group, triazolyl group and tetrazolyl group, among whicha dibenzofuranyl group, dibenzothiophenyl group, carbazolyl group,pyridyl group, pyrimidinyl group, triazinyl group, azadibenzofuranylgroup and azadibenzothiophenyl group may be preferable.

The aromatic heterocyclic group is preferably any one of adibenzofuranyl group, dibenzothiophenyl group, carbazolyl group, pyridylgroup, pyrimidinyl group, triazinyl group, azadibenzofuranyl group andazadibenzothiophenyl group, and further preferably any one of adibenzofuranyl group, dibenzothiophenyl group, azadibenzofuranyl groupand azadibenzothiophenyl group.

Specific examples of the trialkylsilyl group include a trimethylsilylgroup and a triethylsilyl group. Specific examples of the substituted orunsubstituted arylalkylsilyl group include a diphenylmethylsilyl group,ditolylmethylsilyl group and phenyldimethylsilyl group. Specificexamples of the substituted or unsubstituted triarylsilyl group includea triphenylsilyl group and a tritolylsilyl group.

Specific examples of the diaryl phosphine oxide group include a diphenylphosphine oxide group and ditolyl phosphine oxide group.

When R₁, R_(a), Ar₁, Ar₂, Ar₃ and Ar₄ are substituted, examples of thesubstituents include a substituted or unsubstituted alkyl group having 1to 30 carbon atoms, substituted or unsubstituted cycloalkyl group having3 to 30 ring carbon atoms, substituted or unsubstituted trialkylsilylgroup, substituted or unsubstituted arylalkylsilyl group, substituted orunsubstituted triarylsilyl group, substituted or unsubstituted diarylphosphine oxide group, substituted or unsubstituted aromatic hydrocarbonring group having 6 to 30 ring carbon atoms, and substituted orunsubstituted aromatic heterocyclic group having 5 to 30 ring atoms,among which a substituted or unsubstituted aromatic hydrocarbon ringgroup having 6 to 30 ring carbon atoms and substituted or unsubstitutedaromatic heterocyclic group having 5 to 30 ring atoms are preferable.Specific examples of the aromatic hydrocarbon ring group include aphenyl group, tolyl group, xylyl group, naphthyl group, phenanthrylgroup, pyrenyl group, chrysenyl group, benzo[c]phenanthryl group,benzo[g]chrysenyl group, benzoanthryl group, triphenylenyl group,fluorenyl group, 9,9-dimethylfluorenyl group, benzofluorenyl group,dibenzofluorenyl group, biphenyl group, terphenyl group, quarterphenylgroup and fluoranthenyl group. Specific examples of the aromaticheterocyclic group include a pyrrolyl group, pyrazolyl group, pyrazinylgroup, pyrimidinyl group, pyridazynyl group, pyridyl group, triazinylgroup, indolyl group, isoindolyl group, imidazolyl group, benzimidazolylgroup, indazolyl group, imidazo[1,2-a]pyridinyl group, furyl group,benzofuranyl group, isobenzofuranyl group, dibenzofuranyl group,azadibenzofuranyl group, thiophenyl group, benzothiophenyl group,dibenzothiophenyl group, azadibenzothiophenyl group, quinolyl group,isoquinolyl group, quinoxalinyl group, quinazolinyl group,naphthyridinyl group, carbazolyl group, azacarbazolyl group,phenanthridinyl group, acridinyl group, phenanthrolinyl group,phenazinyl group, phenothiazinyl group, phenoxazinyl group, oxazolylgroup, oxadiazolyl group, furazanyl group, benzoxazolyl group, thienylgroup, thiazolyl group, thiadiazolyl group, benzothiazolyl group,triazolyl group and tetrazolyl group.

For an organic EL device including a blue-emitting layer, the aromaticheterocyclic group as a substituent in the third material is preferablya non-fused aromatic heterocyclic group.

Specific examples of the third material of the exemplary embodiment areshown below. It should be noted that the third material according to theinvention may be different from these specific examples.

Relationship Between First Material, Second Material and Third Materialin Emitting Layer

In the exemplary embodiment, the third material is inferred to functionas a dispersant that suppresses molecular association of the secondmaterial of the exemplary embodiment with another in the emitting layer.

The second material of the exemplary embodiment is a thermally activateddelayed fluorescent material, and thus is likely to undergo molecularassociation. An excitation energy of a molecular assembly (i.e., singletenergy and triplet energy) is small as compared with an excitationenergy of a monomer. Therefore, it is predicted that an increase in theconcentration of the second material in the thin film should result inenergy loss attributed to molecular association.

Accordingly, especially when the emitting layer contains a blue-emittingfluorescent material with a large excitation energy, the third materialcontributes to suppressing the energy loss attributed to molecularassociation, which results in improvement in the efficiency of theorganic EL device. Similarly, when the emitting layer contains aluminescent material emitting light with a wavelength ranging from ared-light wavelength range to a yellow-light wavelength range, the thirdmaterial contributes to improving a carrier balance factor, whichresults in improvement in the efficiency of the organic EL device.

Typical fluorescent organic EL device and phosphorescent organic ELdevice seem not to be improved in luminous efficiency by adding thethird material, which has a function different from a function as a hostmaterial and a function as a luminescent material, to the emitting layeras in the exemplary embodiment. In contrast, the thermally activateddelayed fluorescent organic EL device of the exemplary embodiment has apotential for a significant change in a carrier balance factor, because,while the thermally activated delayed fluorescent material with arelatively small singlet energy causes carrier transport in the emittinglayer, the third material with a singlet energy larger than that of thesecond material is unlikely to cause carrier transport. This results incontribution to improvement in the efficiency of the organic EL device.

Since the singlet energy of the third material is larger than that ofthe second material, the excited third material is unstable as comparedwith the first material and the second material. Accordingly, the thirdmaterial preferably has no influence on generation of excitons andcarrier transport in the emitting layer. For a typical organic ELdevice, such a third material is a unique material in view of criteriafor selecting a material to be contained in the emitting layer. Whilethe emitting layer of a typical florescent organic EL device selectivelycontains a material with high electrical and optical functions, theemitting layer of the exemplary embodiment contains the third materialthat has no influence on generation of excitons and carrier transport.

In the exemplary embodiment, a singlet energy EgS(M2) of the secondmaterial is preferably larger than the singlet energy EgS(M1) of thefirst material.

In other words, a relationship of EgS(M1)<EgS(M2)<EgS(M3) is preferablysatisfied.

In the exemplary embodiment, it is preferable that an energy gapEg_(77K)(M2) at 77 [K] of the second material is larger than an energygap Eg_(77K)(M1) at 77 [K] of the first material, and an energy gapEg_(77K)(M3) at 77 [K] of the third material is larger than the energygap Eg_(77K)(M2) at 77 [K] of the second material.

In other words, a relationship of Eg_(77K)(M1)<Eg_(77K)(M2)<Eg_(77K)(M3)is preferably satisfied.

In the exemplary embodiment, a difference ΔST(M2) between the singletenergy EgS(M2) of the second material and the energy gap Eg_(77K)(M2) at77 [K] of the second material preferably satisfies a relationship of anumerical formula (Numerical Formula 1) below.

ΔST(M2)=EgS(M2)−Eg _(77K)(M2)<0.3 [eV]  (Numerical Formula 1)

ΔST(M2) is preferably less than 0.2 [eV].

In the exemplary embodiment, a difference ΔST(M1) between the singletenergy EgS(M1) of the first material and the energy gap Eg_(77K)(M1) at77 [K] of the first material preferably satisfies a relationship of anumerical formula (Numerical Formula 2) below.

ΔST(M1)=EgS(M1)−Eg _(77K)(M1)>0.3 [eV]  (Numerical Formula 2)

In the exemplary embodiment, a difference ΔST(M3) between the singletenergy EgS(M3) of the third material and the energy gap Eg_(77K)(M3) at77[K] of the third material preferably satisfies a relationship of anumerical formula (Numerical Formula 3) below.

ΔST(M3)=EgS(M3)−Eg _(77K)(M3)>0.3 [eV]  (Numerical Formula 3)

In the exemplary embodiment, the Eg_(77K)(M3) at 77 [K] of the thirdmaterial is preferably 2.9 eV or more. When the Eg_(77K)(M3) of thethird material is in the above range, the third material is unlikely toaffect generation of excitons and carrier transport in the emittinglayer.

ΔST

From a quantum chemical viewpoint, decrease in the energy difference(ΔST) between the singlet energy EgS and the triplet energy EgT can beachieved by a small exchange interaction therebetween. Physical detailsof the relationship between ΔST and the exchange interaction aredescribed, for instance, in Reference Document 1 and Reference Document2 below.

-   Reference Document 2: ADACHI, Chihaya, et al. (ed.), Organic EL    Symposium, proceeding for the tenth meeting, S2-5, pp. 11-12-   Reference Document 3: TOKUMURA, Katsumi (ed.) (1973), Yuki Hikari    Kagaku Hanno-ron (Organic Photochemical Reaction Theory), Tokyo    Kagaku Dojin Co., Ltd.

Such a material can be synthesized according to molecular design basedon quantum calculation. Specifically, the material is a compound inwhich a LUMO electron orbit and a HOMO electron orbit are localized toavoid overlapping.

Examples of the compound having a small ΔST used as the second materialof the exemplary embodiment include compounds in which a donor elementis bonded to an acceptor element in a molecule and ΔST is in a range of0 eV or more and less than 0.3 eV in view of electrochemical stability(oxidation-reduction stability).

A more preferable compound is such a compound that dipoles formed in theexcited state of a molecule interact with each other to form anaggregate having a reduced exchange interaction energy. According toanalysis by the inventors, the dipoles are oriented substantially in thesame direction in the compound, so that ΔST can be further reduced bythe interaction of the molecules. In such a case, ΔST can be extremelysmall in a range of 0 eV to 0.2 eV.

TADF Mechanism

In the organic EL device of the exemplary embodiment, the secondmaterial is preferably a compound having a small ΔST(M2) so that inverseintersystem crossing from the triplet energy level of the secondmaterial to the singlet energy level thereof is easily caused by a heatenergy given from the outside. An energy state conversion mechanism toperform spin exchange from the triplet state of electrically excitedexcitons within the organic EL device to the singlet state by inverseintersystem crossing is referred to as a TADF mechanism.

FIG. 4 shows an example of a relationship of energy levels of the first,second and third materials in the emitting layer. In FIG. 4 , S0represents a ground state, S1(M1) represents a lowest singlet state ofthe first material, T1(M1) represents a lowest triplet state of thefirst material, S1(M2) represents a lowest singlet state of the secondmaterial, T1(M2) represents a lowest triplet state of the secondmaterial, S1(M3) represents a lowest singlet state of the thirdmaterial, and T1(M3) represents a lowest triplet state of the thirdmaterial. A dashed arrow directed from S1(M2) to S1(M1) in FIG. 4represents Förster energy transfer from the lowest singlet state of thesecond material to the lowest singlet state of the first material.

As shown in FIG. 4 , when a material having a small ΔST(M2) is used asthe second material, inverse intersystem crossing from the lowesttriplet state T1(M2) to the lowest singlet state S1(M2) can be caused bya heat energy. Consequently, Förster energy transfer from the lowestsinglet state S1(M2) of the second material to the lowest singlet stateS1(M1) of the first material is caused. As a result, fluorescence fromthe lowest singlet state S1(M1) of the first material can be observed.It is inferred that the internal quantum efficiency can be theoreticallyraised up to 100% also by using delayed fluorescence by the TADFmechanism.

Relationship between Triplet Energy and Energy Gap at 77 [K]Descriptionwill be made on a relationship between a triplet energy and an energygap at 77 [K]. In the exemplary embodiment, the energy gap at 77 [K] isdifferent from a typical triplet energy in some aspects.

For the first material and the third material (measurement targets), thetriplet energy is measured as follows. Specifically, a compound to bemeasured is dissolved in EPA (diethylether:isopentane:ethanol=5:5:2 involume ratio) at a concentration of 10 μmol/L, and the resultingsolution is set in a quartz cell to provide a measurement sample. Aphosphorescence spectrum (ordinate axis: phosphorescent luminousintensity, abscissa axis: wavelength) of the measurement sample ismeasured at a low temperature (77 [K]), a tangent is drawn at the riseof the phosphorescence spectrum on the short-wavelength side, and anenergy amount calculated by the following conversion equation 1 based ona wavelength value λ_(edge)[nm] of an intersection between the tangentand the abscissa axis is defined as the energy gap Eg_(77K) at 77 [K].

Eg _(77K) [eV]=1239.85/λ_(edge)  Conversion Equation 1:

For phosphorescence measurement, a spectrophotofluorometer body F-4500(manufactured by Hitachi High-Technologies Corporation) is usable. Itshould be noted that the phosphorescence measuring device may bedifferent from the above device.

The tangent to the rise of the phosphorescence spectrum on theshort-wavelength side is drawn as follows. While moving on a curve ofthe phosphorescence spectrum from the short-wavelength side to themaximum spectral value closest to the short-wavelength side among themaximum spectral values, a tangent is checked at each point on the curvetoward the long-wavelength of the phosphorescence spectrum. Aninclination of the tangent is increased as the curve rises (i.e., avalue of the ordinate axis is increased). A tangent drawn at a point ofthe maximum inclination (i.e., a tangent at an inflection point) isdefined as the tangent to the rise of the phosphorescence spectrum onthe short-wavelength side.

The maximum with peak intensity being 15% or less of the maximum peakintensity of the spectrum is not included in the above-mentioned maximumclosest to the short-wavelength side of the spectrum. The tangent drawnat a point of the maximum spectral value being the closest to theshort-wavelength side and having the maximum inclination is defined as atangent to the rise of the phosphorescence spectrum on theshort-wavelength side.

For the second material (measurement target), the triplet energy ismeasured as follows. A compound to be measured (the second material) anda compound TH-2 are co-deposited on a quartz substrate to prepare asample sealed in an NMR tube. It should be noted that the sample isprepared under the following conditions: quartz substrate/TH-2: secondmaterial (film thickness: 100 nm, concentration of second material: 12mass %).

A phosphorescence spectrum (ordinate axis: phosphorescent luminousintensity, abscissa axis: wavelength) of the measurement sample ismeasured at a low temperature (77 [K]), a tangent is drawn at the riseof the phosphorescence spectrum on the short-wavelength side, and anenergy amount calculated by the following conversion equation 2 based ona wavelength value λ_(edge)[nm] of an intersection between the tangentand the abscissa axis is defined as the energy gap Eg_(77K) at 77 [K].

Eg _(77K) [eV]=1239.85/λ_(edge)  Conversion Equation 2:

For phosphorescence measurement, a spectrophotofluorometer body F-4500(manufactured by Hitachi High-Technologies Corporation) is usable. Itshould be noted that the phosphorescence measuring device may bedifferent from the above device.

The tangent to the rise of the phosphorescence spectrum on theshort-wavelength side is drawn in the same manner as those of thephosphorescence spectra of the first and second materials.

In the exemplary embodiment, a compound having a small ΔST is preferablyusable as the second material. When ΔST is small, intersystem crossingand inverse intersystem crossing are likely to occur even at a lowtemperature (77[K]), so that the singlet state and the triplet statecoexist. As a result, the spectrum to be measured in the same manner asthe above includes emission from both the singlet state and the tripletstate. Although it is difficult to distinguish the emission from thesinglet state from the emission from the triplet state, the value of thetriplet energy is basically considered dominant.

Accordingly, in the exemplary embodiment, the triplet energy is measuredby the same method as a typical triplet energy EgT, but a value measuredin the following manner is referred to as an energy gap Eg_(77K) inorder to differentiate the measured energy from the typical tripletenergy in a strict meaning.

Singlet Energy EgS

The singlet energy EgS is measured as follows.

A 10-μmol/L toluene solution of a compound to be measured is preparedand put in a quartz cell. An absorption spectrum (ordinate axis:luminous intensity, abscissa axis: intensity) of the thus-obtainedsample is measured at a room temperature (300 K). A tangent is drawn atthe rise on the long-wavelength side, and a singlet energy is calculatedby substituting a wavelength value λ_(edge) [nm] of an intersectionbetween the tangent and the abscissa axis into the following conversionequation 3.

EgS [eV]=1239.85/λ_(edge)  Conversion Equation 3:

In Example, the absorption spectrum is measured using aspectrophotometer manufactured by Hitachi, Ltd. (device name: U3310). Itshould be noted that the absorption spectrum measuring device may bedifferent from the above device.

In the exemplary embodiment, a difference between the singlet energy EgSand the energy gap Eg_(77K) is defined as ΔST.

In the exemplary embodiment, an ionization potential Ip(M3) of the thirdmaterial and an ionization potential Ip(M2) of the second materialpreferably satisfy a relationship of a numerical formula (NumericalFormula 4) below. When this relationship is satisfied, the thirdmaterial is unlikely to affect generation of excitons and carriertransport in the emitting layer.

Ip(M3)≥Ip(M2)  (Numerical Formula 4)

In the exemplary embodiment, the ionization potential Ip(M 3) of thethird material is preferably 6.3 eV or more. When the ionizationpotential Ip(M3) of the third material is in the above range, the thirdmaterial is unlikely to affect generation of excitons and carriertransport in the emitting layer.

It should be noted that an ionization potential can be measured using aphotoelectron spectroscopy device under the atmosphere. Specifically, amaterial is irradiated with light and the amount of electrons generatedby charge separation is measured. The measuring device may be aphotoelectron spectroscopy device manufactured by RIKEN KEIKI Co., Ltd.(device name: AC-3).

In the exemplary embodiment, an electron affinity Af(M3) of the thirdmaterial and an electron affinity Af(M2) of the second materialpreferably satisfy a relationship of a numerical formula (NumericalFormula 5) below. When this relationship is satisfied, the thirdmaterial is unlikely to affect generation of excitons and carriertransport in the emitting layer.

Af(M3)≤Af(M2)  (Numerical Formula 5)

In the exemplary embodiment, the electron affinity Af(M3) of the thirdmaterial is preferably 2.8 eV or more. When the electron affinity Af(M3)of the third material is in the above range, the third material isunlikely to affect generation of excitons and carrier transport in theemitting layer.

The electron affinity can be calculated by a numerical formula(Numerical Formula 8) below from the measurement values of theionization potential Ip and singlet energy EgS of the compound measuredin the above manner.

Af=Ip−EgS  (Numerical Formula 8)

Film Thickness of Emitting Layer

A film thickness of the emitting layer of the organic EL device of theexemplary embodiment is preferably in a range from 5 nm to 50 nm, morepreferably in a range from 7 nm to 50 nm, and most preferably in a rangefrom 10 nm to 50 nm. The thickness of less than 5 nm may causedifficulty in forming the emitting layer and in controllingchromaticity, while the thickness of more than 50 nm may raise drivevoltage.

Content Ratio of Materials in Emitting Layer

In the emitting layer of the organic EL device of the exemplaryembodiment, it is preferable that the content ratio of the firstemitting layer is in a range from 0.01 mass % to 10 mass %, the contentratio of the second material is in a range from 1 mass % to 75 mass %,and the content ratio of the third material is in a range from 1 mass %to 75 mass %. An upper limit of the total of the respective contentratios of the first to third materials in the emitting layer is 100 mass%. It should be noted that the emitting layer of the exemplaryembodiment may further contain another material in addition to the firstto third materials.

Substrate

A substrate is used as a support for the organic EL device. Forinstance, glass, quartz, plastics and the like are usable as thesubstrate. A flexible substrate is also usable. The flexible substrateis a bendable substrate, which is exemplified by a plastic substrateformed of polycarbonate, polyarylate, polyethersulfone, polypropylene,polyester, polyvinyl fluoride, polyvinyl chloride, polyimide, andpolyethylene naphthalate. Moreover, an inorganic vapor deposition filmis also usable.

Anode

Metal, alloy, an electrically conductive compound and a mixture thereof,which have a large work function, specifically, of 4.0 eV or more, ispreferably usable as the anode formed on the substrate. Specificexamples of the material for the anode include indium tin oxide (ITO),indium tin oxide containing silicon or silicon oxide, indium zinc oxide,tungsten oxide, indium oxide containing zinc oxide and graphene. Inaddition, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chrome(Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium(Pd), titanium (Ti), or nitrides of a metal material (e.g., titaniumnitride) are usable.

The above materials are typically deposited as a film by sputtering. Forinstance, indium zinc oxide can be deposited as a film by sputteringusing a target that is obtained by adding zinc oxide in a range from 1mass % to 10 mass % to indium oxide. Moreover, for instance, indiumoxide containing tungsten oxide and zinc oxide can be deposited as afilm by sputtering using a target that is obtained by adding tungstenoxide in a range from 0.5 mass % to 5 mass % and zinc oxide in a rangefrom 0.1 mass % to 1 mass % to indium oxide. In addition, vapordeposition, coating, ink jet printing, spin coating and the like may beused for forming a film.

Among EL layers formed on the anode, a hole injecting layer formedadjacent to the anode is formed of a composite material that facilitatesinjection of holes irrespective of the work function of the anode.Accordingly, a material usable as an electrode material (e.g., metal,alloy, an electrically conductive compound, a mixture thereof, andelements belonging to Groups 1 and 2 of the periodic table of theelements) is usable as the material for the anode.

The elements belonging to Groups 1 and 2 of the periodic table of theelements, which are materials having a small work function, namely, analkali metal such as lithium (Li) and cesium (Cs) and an alkaline earthmetal such as magnesium (Mg), calcium (Ca) and strontium (Sr), alloythereof (e.g., MgAg, AlLi), a rare earth metal such as europium (Eu) andytterbium (Yb), and alloy thereof are also usable as the material forthe anode. When the anode is formed of the alkali metal, alkaline earthmetal and alloy thereof, vapor deposition and sputtering are usable.Further, when the anode is formed of silver paste and the like, coating,ink jet printing and the like are usable.

Cathode

Metal, alloy, an electrically conductive compound, a mixture thereof andthe like, which have a small work function, specifically, of 3.8 eV orless, is preferably usable as a material for the cathode. Specificexamples of the material for the cathode include: the elements belongingto Groups 1 and 2 of the periodic table of the elements, namely, analkali metal such as lithium (Li) and cesium (Cs) and an alkaline earthmetal such as magnesium (Mg), calcium (Ca) and strontium (Sr); alloythereof (e.g., MgAg, AlLi); a rare earth metal such as europium (Eu) andytterbium (Yb); and alloy thereof.

When the cathode is formed of the alkali metal, alkaline earth metal andalloy thereof, vapor deposition and sputtering are usable. Moreover,when the anode is formed of silver paste and the like, coating, ink jetprinting and the like are usable.

By providing an electron injecting layer, various conductive materialssuch as A1, Ag, ITO, graphene and indium tin oxide containing silicon orsilicon oxide are usable for forming the cathode irrespective of themagnitude of the work function. The conductive materials can bedeposited as a film by sputtering, ink jet printing, spin coating andthe like.

Hole Injecting Layer

A hole injecting layer is a layer containing a highly hole-injectablesubstance. Examples of the highly hole-injectable substance includemolybdenum oxide, titanium oxide, vanadium oxide, rhenium oxide,ruthenium oxide, chromium oxide, zirconium oxide, hafnium oxide,tantalum oxide, silver oxide, tungsten oxide, and manganese oxide.

In addition, the examples of the highly hole-injectable substancefurther include: an aromatic amine compound, which is a low-moleculecompound, such that 4,4′,4″-tris(N,N-diphenylamino)triphenylamine(abbreviation: TDATA),4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine(abbreviation: MTDATA),4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl(abbreviation:DPAB),4,4′-bis(N-{4-[N′-(3-methylphenyl)-N′-phenylamino]phenyl}-N-phenylamino)biphenyl(abbreviation: DNTPD),1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene(abbreviation: DPA3B),3-[N-(9-phenylcarbazole-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA1),3,6-bis[N-(9-phenylcarbazole-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA2), and3-[N-(1-naphthyl)-N-(9-phenylcarbazole-3-yl)amino]-9-phenylcarbazole(abbreviation: PCzPCN1); anddipyrazino[2,3-f:20,30-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile(HAT-CN).

Moreover, a high-molecule compound (e.g., an oligomer, dendrimer andpolymer) is also usable as the highly hole-injectable substance.Examples of the high-molecule compound include poly(N-vinylcarbazole)(abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA),poly[N-(4-{N′-[4-(4-diphenylamino)phenyl]phenyl-N′-phenylamino}phenyl)methacrylamido](abbreviation: PTPDMA), andpoly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine] (abbreviation:Poly-TPD). Furthermore, the examples of the high-molecule compoundinclude a high-molecule compound added with an acid such aspoly(3,4-ethylene dioxythiophene)/poly(styrene sulfonic acid)(PEDOT/PSS), and polyaniline/poly(styrene sulfonic acid) (PAni/PSS).

Hole Transporting Layer

A hole transporting layer is a layer containing a highlyhole-transportable substance. An aromatic amine compound, carbazolederivative, anthracene derivative and the like are usable for the holetransporting layer. Specific examples of a material for the holetransporting layer include4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB),N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(abbreviation: TPD), 4-phenyl-4′-(9-phenylfluorene-9-yl)triphenylamine(abbreviation: BAFLP),4,4′-bis[N-(9,9-dimethylfluorene-2-yl)-N-phenylamino]biphenyl(abbreviation: DFLDPBi), 4,4′,4″-tris(N,N-diphenylamino)triphenylamine(abbreviation: TDATA),4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine(abbreviation: MTDATA), and4,4′-bis[N-(spiro-9,9′-bifluorene-2-yl)-N-phenylamino]biphenyl(abbreviation: BSPB). The above-described substances mostly have a holemobility of 10⁻⁶ cm²/(V·s) or more.

A hole transporting layer is a layer containing a highlyhole-transportable substance. An aromatic amine compound, carbazolederivative, anthracene derivative and the like are usable for the holetransporting layer. Specific examples of a material for the holetransporting layer include4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB),N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(abbreviation: TPD), 4-phenyl-4′-(9-phenylfluorene-9-yl)triphenylamine(abbreviation: BAFLP),4,4′-bis[N-(9,9-dimethylfluorene-2-yl)-N-phenylamino]biphenyl(abbreviation: DFLDPBi), 4,4′,4″-tris(N,N-diphenylamino)triphenylamine(abbreviation: TDATA),4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine(abbreviation: MTDATA), and4,4′-bis[N-(spiro-9,9′-bifluorene-2-yl)-N-phenylamino]biphenyl(abbreviation: BSPB). The above-described substances mostly have a holemobility of 10⁻⁶ cm²/(V·s) or more.

However, any substance having a hole transporting performance higherthan an electron transporting performance may be used in addition to theabove substances. A highly hole-transportable substance may be providedin the form of a single layer or a laminated layer of two or more layersof the above substance.

When the hole transporting layer includes two or more layers, one of thelayers with a larger energy gap is preferably provided closer to theemitting layer. Examples of such a material include HT-2, which is usedin Examples described later.

Electron Transporting Layer

An electron transporting layer is a layer containing a highlyelectron-transportable substance. As the electron transporting layer, 1)a metal complex such as an aluminum complex, beryllium complex and zinccomplex, 2) heteroaromatic compound such as an imidazole derivative,benzimidazole derivative, azine derivative, carbazole derivative, andphenanthroline derivative, and 3) a high-molecule compound are usable.Specifically, as a low-molecule organic compound, a metal complex suchas Alq, tris(4-methyl-8-quinolinato)aluminum (abbreviation: Almq3),bis(10-hydroxybenzo[h]quinolinato)beryllium (abbreviation: BeBq2), BAlq,Znq, ZnPBO and ZnBTZ are usable. In addition to the metal complex, aheteroaromatic compound such as2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD), 1,3-bis[5-(ptert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene(abbreviation: OXD-7),3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenyl)-1,2,4-triazole(abbreviation: TAZ),3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenyl)-1,2,4-triazole(abbreviation: p-EtTAZ), bathophenanthroline (abbreviation: BPhen),bathocuproine (abbreviation: BCP), and4,4′-bis(5-methylbenzoxazole-2-yl)stilbene (abbreviation: BzOs) areusable. In the exemplary embodiment, a benzimidazole compound issuitably usable. The above-described substances mostly have an electronmobility of 10⁻⁶ cm²/(V·s) or more. However, any substance having anelectron transporting performance higher than a hole transportingperformance may be used for the electron transporting layer in additionto the above substances. The electron transporting layer may be providedin the form of a single layer or a laminated layer of two or more layersof the above substance(s).

Moreover, a high-molecule compound is also usable for the electrontransporting layer. For instance,poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)](abbreviation:PF-Py),poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2′-bipyridine-6,6′-diyl)](abbreviation:PF-BPy) and the like are usable.

Electron Injecting Layer

An electron injecting layer is a layer containing a highlyelectron-injectable substance. Examples of a material for the electroninjecting layer include an alkali metal, alkaline earth metal and acompound thereof, examples of which include lithium (Li), cesium (Cs),calcium (Ca), lithium fluoride (LiF), cesium fluoride (CsF), calciumfluoride (CaF2), and lithium oxide (LiOx). In addition, a compoundcontaining an alkali metal, alkaline earth metal and a compound thereofin the electron transportable substance, specifically, a compoundcontaining magnesium (Mg) in Alq and the like may be used. With thiscompound, electrons can be more efficiently injected from the cathode.

Alternatively, a composite material provided by mixing an organiccompound with an electron donor may be used for the electron injectinglayer. The composite material exhibits excellent electron injectingperformance and electron transporting performance since the electrondonor generates electron in the organic compound. In this arrangement,the organic compound is preferably a material exhibiting an excellenttransforming performance of the generated electrons. Specifically, forinstance, the above-described substance for the electron transportinglayer (e.g., the metal complex and heteroaromatic compound) is usable.The electron donor may be any substance exhibiting an electron donatingperformance to the organic compound. Specifically, an alkali metal,alkaline earth metal and a rare earth metal are preferable, examples ofwhich include lithium, cesium, magnesium, calcium, erbium and ytterbium.Moreover, an alkali metal oxide and alkaline earth metal oxide arepreferable, examples of which include lithium oxide, calcium oxide, andbarium oxide. Further, Lewis base such as magnesium oxide is alsousable. Furthermore, tetrathiafulvalene (abbreviation: TTF) is alsousable.

Layer Formation Method(s)

A method for forming each layer of the organic EL device is subject tono limitation except for the above particular description. However,known methods of dry film-forming such as vacuum deposition, sputtering,plasma or ion plating and wet film-forming such as spin coating,dipping, flow coating or ink-jet are applicable.

Film Thickness

The thickness of each organic layer of the organic EL device in theexemplary embodiment is subject to no limitation except for thethickness particularly described above. However, the thickness istypically preferably in a range of several nanometers to 1 μm because anexcessively thin film is likely to entail defects such as a pin holewhile an excessively thick film requires high applied voltage anddeteriorates efficiency.

Herein, the number of carbon atoms forming a ring (also referred to asring carbon atoms) means the number of carbon atoms included in atomsforming the ring itself of a compound in which the atoms are bonded toform the ring (e.g., a monocyclic compound, a fused ring compound, across-linked compound, a carbocyclic compound, and a heterocycliccompound). When the ring is substituted by a substituent, the “ringcarbon atoms” do not include carbon(s) contained in the substituent.Unless specifically described, the same applies to the “ring carbonatoms” described later. For instance, a benzene ring has 6 ring carbonatoms, a naphthalene ring has 10 ring carbon atoms, a pyridinyl grouphas 5 ring carbon atoms, and a furanyl group has 4 ring carbon atoms.When the benzene ring and/or the naphthalene ring is substituted by, forinstance, an alkyl group, the number of carbon atoms of the alkyl groupis not included in the number of the ring carbon atoms. When a fluorenering is substituted by, for instance, a fluorene ring (e.g., aspirofluorene ring), the number of carbon atoms of the fluorene ring asa substituent is not counted in the number of the ring carbon atoms forthe fluorene ring.

Herein, the number of atoms forming a ring (also referred to as ringatoms) means the number of atoms forming the ring itself of a compoundin which the atoms are bonded to form the ring (e.g., a monocycliccompound, a fused ring compound, a cross-linked compound, a carbocycliccompound, and a heterocyclic compound). Atom(s) not forming the ring(e.g., a hydrogen atom for terminating the atoms forming the ring) andatoms included in a substituent substituting the ring are not counted inthe number of the ring atoms. Unless specifically described, the sameapplies to the “ring atoms” described later. For instance, a pyridinering has 6 ring atoms, a quinazoline ring has 10 ring atoms, and a furanring has 5 ring atoms. Hydrogen atoms respectively bonded to thepyridine ring and the quinazoline ring and atoms forming thesubstituents are not counted in the number of the ring atoms. When afluorene ring is substituted by, for instance, a fluorene ring (e.g., aspirofluorene ring), the number of atoms of the fluorene ring as asubstituent is not included in the number of the ring atoms for thefluorene ring.

Next, each of substituents described in the above formulae will bedescribed.

In the exemplary embodiment, examples of the aromatic hydrocarbon groupgroup having 6 to 30 ring carbon atoms include a phenyl group, biphenylgroup, terphenyl group, naphthyl group, anthryl group, phenanthrylgroup, fluorenyl group, pyrenyl group, chrysenyl group, fluoranthenylgroup, benzo[a]anthryl group, benzo[c]phenanthryl group, triphenylenylgroup, benzo[k]fluoranthenyl group, benzo[g]chrysenyl group,benzo[b]triphenylenyl group, picenyl group, and perylenyl group.

The aryl group in the exemplary embodiment preferably has 6 to 20 ringcarbon atoms, and more preferably 6 to 12 ring carbon atoms. Among theabove aryl group, a phenyl group, biphenyl group, naphthyl group,phenanthryl group, terphenyl group, and fluorenyl group are particularlypreferable. A carbon atom at a position 9 of each of 1-fluorenyl group,2-fluorenyl group, 3-fluorenyl group and 4-fluorenyl group is preferablysubstituted by a substituted or unsubstituted alkyl group having 1 to 30carbon atoms or a substituted or unsubstituted aryl group having 6 to 18ring carbon atoms later described in the exemplary embodiment.

The heterocyclic group (occasionally, referred to as hetroaryl group,heteroaromatic ring group or aromatic heterocyclic group) having 5 to 30ring atoms preferably contains at least one atom selected from the groupconsisting of nitrogen, sulfur, oxygen, silicon, selenium atom andgermanium atom, and more preferably contains at least one atom selectedfrom the group consisting of nitrogen, sulfur and oxygen.

Examples of the heterocyclic group (heteroaryl group) having 5 to 30ring atoms in the exemplary embodiment include a pyridyl group,pyrimidinyl group, pyrazinyl group, pyridazynyl group, triazinyl group,quinolyl group, isoquinolinyl group, naphthyridinyl group, phthalazinylgroup, quinoxalinyl group, quinazolinyl group, phenanthridinyl group,acridinyl group, phenanthrolinyl group, pyrrolyl group, imidazolylgroup, pyrazolyl group, triazolyl group, tetrazolyl group, indolylgroup, benzimidazolyl group, indazolyl group, imidazopyridinyl group,benzotriazolyl group, carbazolyl group, furyl group, thienyl group,oxazolyl group, thiazolyl group, isoxazolyl group, isothiazolyl group,oxadiazolyl group, thiadiazolyl group, benzofuranyl group,benzothiophenyl group, benzoxazolyl group, benzothiazolyl group,benzisoxazolyl group, benzisothiazolyl group, benzoxadiazolyl group,benzothiadiazolyl group, dibenzofuranyl group, dibenzothiophenyl group,piperidinyl group, pyrrolidinyl group, piperazinyl group, morpholylgroup, phenazinyl group, phenothiazinyl group, and phenoxazinyl group.

The heterocyclic group in the exemplary embodiment preferably has 5 to20 ring atoms, more preferably 5 to 14 ring atoms. Among the aboveheterocyclic group, a 1-dibenzofuranyl group, 2-dibenzofuranyl group,3-dibenzofuranyl group, 4-dibenzofuranyl group, 1-dibenzothiophenylgroup, 2-dibenzothiophenyl group, 3-dibenzothiophenyl group,4-dibenzothiophenyl group, 1-carbazolyl group, 2-carbazolyl group,3-carbazolyl group, 4-carbazolyl group, and 9-carbazolyl group areparticularly preferable. A nitrogen atom at a position 9 of each of1-carbazolyl group, 2-carbazolyl group, 3-carbazolyl group and4-carbazolyl group is preferably substituted by a substituted orunsubstituted aryl group having 6 to 30 ring carbon atoms or asubstituted or unsubstituted heterocyclic group having 5 to 30 ringatoms in the exemplary embodiment.

In the exemplary embodiment, the heterocyclic group may be a groupderived from any one of moieties represented by formulae (XY-1) to(XY-18).

In the formulae (XY-1) to (XY-18), X and Y each independently representa hetero atom, and preferably represent an oxygen atom, sulfur atom,selenium atom, silicon atom or germanium atom. The moieties representedby the formulae (XY-1) to (XY-18) may each be bonded in any position tobe a heterocyclic group, which may be substituted.

In the exemplary embodiment, examples of the substituted orunsubstituted carbazolyl group may include a group in which a carbazolering is further fused with a ring(s) as shown in the following formulae.Such a group may be substituted. The group may be bonded in any positionas desired.

The alkyl group having 1 to 30 carbon atoms in the exemplary embodimentis preferably linear, branched or cyclic. Examples of the linear orbranched alkyl group include: a methyl group, ethyl group, n-propylgroup, isopropyl group, n-butyl group, s-butyl group, isobutyl group,t-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octylgroup, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group,n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecylgroup, n-heptadecyl group, n-octadecyl group, neopentyl group, amylgroup, isoamyl group, 1-methylpentyl group, 2-methylpentyl group,1-pentylhexyl group, 1-butylpentyl group, 1-heptyloctyl group, and3-methylpentyl group.

The linear or branched alkyl group in the exemplary embodimentpreferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbonatoms. Among the linear or branched alkyl group, a methyl group, ethylgroup, propyl group, isopropyl group, n-butyl group, s-butyl group,isobutyl group, t-butyl group, n-pentyl group, n-hexyl group, amylgroup, isoamyl group, and neopentyl group are particularly preferable.

Examples of the cycloalkyl group in the exemplary embodiment include acyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexylgroup, 4-methylcyclohexyl group, adamantyl group and norbornyl group.The cycloalkyl group preferably has 3 to 10 ring carbon atoms, morepreferably 5 to 8 ring carbon atoms. Among the above cycloalkyl group, acyclopentyl group and a cyclohexyl group are particularly preferable.

A halogenated alkyl group provided by substituting the alkyl group witha halogen atom is exemplified by a halogenated alkyl group provided bysubstituting the alkyl group having 1 to 30 carbon atoms with one ormore halogen groups. Specific examples of the halogenated alkyl groupincludes a fluoromethyl group, difluoromethyl group, trifluoromethylgroup, fluoroethyl group, trifluoromethylmethyl group, trifluoroethylgroup, and pentafluoroethyl group.

The alkylsilyl group having 3 to 30 carbon atoms in the exemplaryembodiment is exemplified by a trialkylsilyl group having the abovealkyl group having 1 to 30 carbon atoms. Specific examples of thetrialkylsilyl group include a trimethylsilyl group, triethylsilyl group,tri-n-butylsilyl group, tri-n-octylsilyl group, triisobutylsilyl group,dimethylethylsilyl group, dimethylisopropylsilyl group,dimethyl-n-propylsilyl group, dimethyl-n-butylsilyl group,dimethyl-t-butylsilyl group, diethylisopropylsilyl group,vinyldimethylsilyl group, propyldimethylsilyl group andtriisopropylsilyl group. Three alkyl groups in the trialkylsilyl groupmay be mutually the same or different.

Examples of the arylsilyl group having 6 to 30 ring carbon atoms in theexemplary embodiment include a dialkylarylsilyl group, alkyldiarylsilylgroup and triarylsilyl group.

The dialkylarylsilyl group is exemplified by a dialkylarylsilyl grouphaving two of the examples of the alkyl group having 1 to 30 carbonatoms and one of the aryl group having 6 to 30 ring carbon atoms. Thedialkylarylsilyl group preferably has 8 to 30 carbon atoms.

The alkyldiarylsilyl group is exemplified by an alkyldiarylsilyl grouphaving one of the examples of the alkyl group having 1 to 30 carbonatoms and two of the aryl group having 6 to 30 ring carbon atoms. Thedialkylarylsilyl group preferably has 13 to 30 carbon atoms.

The triarylsilyl group is exemplified by a triarylsilyl group havingthree of the aryl group having 6 to 30 ring carbon atoms. Thetriarylsilyl group preferably has 18 to 30 carbon atoms.

The alkoxy group having 1 to 30 carbon atoms in the exemplary embodimentis represented by —OZ₁. Z₁ is exemplified by the above alkyl grouphaving 1 to 30 carbon atoms. Examples of the alkoxy group include amethoxy group, ethoxy group, propoxy group, butoxy group, pentyloxygroup and hexyloxy group. The alkoxy group preferably has 1 to 20 carbonatoms.

A halogenated alkoxy group provided by substituting the alkoxy groupwith a halogen atom is exemplified by a halogenated alkoxy groupprovided by substituting the alkoxy group having 1 to 30 carbon atomswith one or more halogen groups.

The aryloxy group having 6 to 30 ring carbon atoms in the exemplaryembodiment is represented by —OZ₂. Z₂ is exemplified by the above arylgroup having 6 to 30 ring carbon atoms. The aryloxy group preferably has6 to 20 ring carbon atoms. The aryloxy group is exemplified by a phenoxygroup.

The alkylamino group having 2 to 30 carbon atoms is represented by—NHR_(V) or —N(R_(V))₂. R_(V) is exemplified by the alkyl group having 1to 30 carbon atoms.

The arylamino group having 6 to 60 ring carbon atoms is represented by—NHR_(W) or —N(R_(W))₂. R_(W) is exemplified by the above aryl grouphaving 6 to 30 ring carbon atoms.

The alkylthio group having 1 to 30 carbon atoms is represented by—SR_(V). R_(V) is exemplified by the alkyl group having 1 to 30 carbonatoms. The alkylthio group preferably has 1 to 20 carbon atoms.

The arylthio group having 6 to 30 ring carbon atoms is represented by—SR_(W). R_(W) is exemplified by the above aryl group having 6 to 30ring carbon atoms. The arylthio group preferably has 6 to 20 ring carbonatoms.

Herein, “carbon atoms forming a ring (ring carbon atoms)” mean carbonatoms forming a saturated ring, unsaturated ring, or aromatic ring.“Atoms forming a ring (ring atoms)” mean carbon atoms and hetero atomsforming a hetero ring including a saturated ring, unsaturated ring, oraromatic ring.

Herein, a “hydrogen atom” means isotopes having different neutronnumbers and specifically encompasses protium, deuterium and tritium.

Herein, examples of substituents in the exemplary embodiment, such asthe substituent meant by “substituted or unsubstituted” and thesubstituent in the cyclic structures A, B, E, F and G, are an alkenylgroup, alkynyl group, aralkyl group, halogen atom, cyano group, hydroxylgroup, nitro group and carboxy group, in addition to the above-describedaryl group, heterocyclic group, alkyl group (linear or branched alkylgroup, cycloalkyl group and haloalkyl group), alkylsilyl group,arylsilyl group, alkoxy group, aryloxy group, alkylamino group,arylamino group, alkylthio group, and arylthio group.

In the above-described substituents, the aryl group, heterocyclic group,alkyl group, halogen atom, alkylsilyl group, arylsilyl group and cyanogroup are preferable. The preferable ones of the specific examples ofeach substituent are further preferable.

These substituents may be further substituted by the abovesubstituent(s). In addition, plural ones of these substituents may bemutually bonded to form a ring.

The alkenyl group is preferably an alkenyl group having 2 to 30 carbonatoms, which may be linear, branched or cyclic. Examples of the alkenylgroup include a vinyl group, propenyl group, butenyl group, oleyl group,eicosapentaenyl group, docosahexaenyl group, styryl group,2,2-diphenylvinyl group, 1,2,2-triphenylvinyl group, 2-phenyl-2-propenylgroup, cyclopentadienyl group, cyclopentenyl group, cyclohexenyl group,and cyclohexadienyl group.

The alkynyl group is preferably an alkynyl group having 2 to 30 carbonatoms, which may be linear, branched or cyclic. Examples of the alkynylgroup include ethynyl, propynyl, and 2-phenylethynyl.

The aralkyl group is preferably an aralkyl group having 6 to 30 ringcarbon atoms and is represented by —Z₃—Z₄. Z₃ is exemplified by analkylene group derived from the above alkyl group having 1 to 30 carbonatoms. Z₄ is exemplified by the above aryl group having 6 to 30 ringcarbon atoms. This aralkyl group is preferably an aralkyl group having 7to 30 carbon atoms, in which an aryl moiety has 6 to 30 carbon atoms,preferably 6 to 20 carbon atoms, more preferably 6 to 12 carbon atomsand an alkyl moiety has 1 to 30 carbon atoms, preferably 1 to 20 carbonatoms, more preferably 1 to 10 carbon atoms, further preferably 1 to 6carbon atoms. Examples of the aralkyl group include a benzyl group,2-phenylpropane-2-yl group, 1-phenylethyl group, 2-phenylethyl group,1-phenylisopropyl group, 2-phenylisopropyl group, phenyl-t-butyl group,α-naphthylmethyl group, 1-α-naphthylethyl group, 2-α-naphthylethylgroup, 1-α-naphthylisopropyl group, 2-α-naphthylisopropyl group,β-naphthylmethyl group, 1-β-naphthylethyl group, 2-β-naphthylethylgroup, 1-β-naphthylisopropyl group, and 2-β-naphthylisopropyl group.

Examples of the halogen atom include a fluorine atom, chlorine atom,bromine tom and iodine atom, among which a fluorine atom is preferable.

“Unsubstituted” in “substituted or unsubstituted” herein means that agroup is not substituted by the above-described substituents but bondedwith a hydrogen atom.

Herein, “XX to YY carbon atoms” in the description of “substituted orunsubstituted ZZ group having XX to YY carbon atoms” represent carbonatoms of an unsubstituted ZZ group and do not include carbon atoms of asubstituent(s) of the substituted ZZ group. Herein, “YY” is larger than“XX.” “XX” and “YY” each mean an integer of 1 or more.

Herein, “XX to YY atoms” in the description of “substituted orunsubstituted ZZ group having XX to YY atoms” represent atoms of anunsubstituted ZZ group and does not include atoms of a substituent(s) ofthe substituted ZZ group. Herein, “YY” is larger than “XX.” “XX” and“YY” each mean an integer of 1 or more.

The same description as the above applies to “substituted orunsubstituted” in the following compound or a partial structure thereof.

Herein, examples of the multiple linking group including bonded 2 to 4groups selected from the above aromatic hydrocarbon groups, the multiplelinking group including bonded 2 to 4 groups selected from the aboveheterocyclic groups, or the multiple linking group including bonded 2 to4 groups selected from the above aromatic hydrocarbon groups andheterocyclic groups include a divalent group including bonded two orfour groups selected from the above aromatic hydrocarbon groups andheterocyclic groups. Examples of the multiple linking group including 2to 4 groups selected from the above aromatic hydrocarbon groups andheterocyclic groups include a heterocyclic group-aromatic hydrocarbongroup, aromatic hydrocarbon group-heterocyclic group, aromatichydrocarbon group-heterocyclic group-aromatic hydrocarbon group,heterocyclic group-aromatic hydrocarbon group-heterocyclic group,aromatic hydrocarbon group-heterocyclic group-aromatic hydrocarbongroup-heterocyclic group, and heterocyclic group-aromatic hydrocarbongroup-heterocyclic group-aromatic hydrocarbon group. Among the above,divalent groups including one of the above aromatic hydrocarbon groupsand one of the above heterocyclic groups, i.e., heterocyclicgroup-aromatic hydrocarbon group and aromatic hydrocarbongroup-heterocyclic group, are preferable. It should be noted thatspecific examples of the aromatic hydrocarbon group and the heterocyclicgroup in the multiple linking group include the above groups describedas the aromatic hydrocarbon group and the heterocyclic group.

The organic EL device of the exemplary embodiment is usable in anelectronic device. Examples of the electronic device include a displayunit and a light-emitting unit. Examples of the display unit includedisplay components such as en organic EL panel module, TV, mobile phone,tablet, and personal computer. Examples of the light-emitting unitinclude an illuminator and a vehicle light.

MODIFICATIONS OF EMBODIMENT(S)

It should be noted that the invention is not limited to the exemplaryembodiment. The invention may include any modification and improvementcompatible with the invention.

The emitting layer is not limited to a single layer, but may be providedas laminate by a plurality of emitting layers. When the organic ELdevice includes a plurality of emitting layers, it is only required thatat least one of the emitting layers includes the first to thirdmaterials. The other emitting layers may each be a fluorescent emittinglayer, or a phosphorescent emitting layer that emits light throughdirect electron transfer from triplet state to ground state.

When the organic EL device includes the plurality of emitting layers,the plurality of emitting layers may be adjacent to each other or aso-called tandem organic EL device in which a plurality of emittingunits are laminated through an intermediate layer.

For instance, a blocking layer may be provided in contact with ananode-side or a cathode-side of the emitting layer. The blocking layeris preferably provided in contact with the emitting layer to block atleast either of excitons and exciplexes.

In contrast, when the blocking layer is provided in contact with thecathode-side of the emitting layer, the blocking layer permits transportof electrons, but prevents holes from reaching a layer provided near thecathode (e.g., the electron transporting layer) beyond the blockinglayer.

For instance, when the blocking layer is provided in contact with theanode-side of the emitting layer, the blocking layer permits transportof holes, but prevents electrons from reaching a layer provided near theanode (e.g., the electron transporting layer) beyond the blocking layer.

Further, a blocking layer may be provided in contact with the emittinglayer to prevent an excitation energy from leaking from the emittinglayer into a layer in the vicinity thereof. Excitons generated in theemitting layer are prevented from moving into a layer provided near theelectrode (e.g., an electron transporting layer and a hole transportinglayer) beyond the blocking layer.

The emitting layer and the blocking layer are preferably bonded to eachother.

Further, specific arrangements and configurations for practicing theinvention may be altered to other arrangements and configurationscompatible with the invention.

EXAMPLE(S)

Examples of the invention will be described below. However, theinvention is not limited to Examples.

Compounds used in Examples are as follows.

Evaluation of Compounds

Next, properties of the compounds used in Examples were measured. Ameasurement method and a calculation method are described below.Measurement results and calculation results are shown in Table 5.

Singlet Energy EgS

The singlet energy EgS was measured as follows.

A 10-μmol/L toluene solution of a compound to be measured was preparedand put in a quartz cell. An absorption spectrum (ordinate axis:luminous intensity, abscissa axis: intensity) of the thus-obtainedsample was measured at a room temperature (300 K). A tangent was drawnat the rise on the long-wavelength side, and a singlet energy wascalculated by substituting a wavelength value λ_(edge) [nm] of anintersection between the tangent and the abscissa axis into thefollowing conversion equation 3.

EgS [eV]=1239.85/λ_(edge)  Conversion Equation 3:

In Example, the absorption spectrum was measured using aspectrophotometer manufactured by Hitachi, Ltd. (device name: U3310).

The tangent to the fall of the absorption spectrum on thelong-wavelength side was drawn as follows. While moving on a curve ofthe absorption spectrum from the maximum spectral value closest to thelong-wavelength side in a long-wavelength direction, a tangent at eachpoint on the curve was checked. An inclination of the tangent wasdecreased and increased in a repeated manner as the curve fell (i.e., avalue of the ordinate axis was decreased). A tangent drawn at a point ofthe minimum inclination closest to the long-wavelength side (except whenabsorbance was 0.1 or less) was defined as the tangent to the fall ofthe absorption spectrum on the long-wavelength side.

The maximum absorbance of 0.2 or less was not included in theabove-mentioned maximum absorbance on the long-wavelength side.

Energy Gap Eg _(77K) at 77 [K]

For the first material and the third material (measurement targets), thetriplet energy was measured as follows. The compound MT-1 and thecompound MT-3 were to be measured. The compound to be measured wasdissolved in EPA (diethylether:isopentane:ethanol=5:5:2 in volume ratio)at a concentration of 10 μmol/L, and the resulting solution was set in aquartz cell to provide a measurement sample. A phosphorescence spectrum(ordinate axis: phosphorescent luminous intensity, abscissa axis:wavelength) of the measurement sample was measured at a low temperature(77 [K]), a tangent was drawn at the rise of the phosphorescencespectrum on the short-wavelength side, and an energy amount calculatedby the following conversion equation 1 based on a wavelength valueλ_(edge) [nm] of an intersection between the tangent and the abscissaaxis was defined as the energy gap Eg_(77K) at 77 [K].

Eg _(77K) [eV]=1239.85/λ_(edge)  Conversion Equation 1:

For the second material (measurement target), the triplet energy wasmeasured as follows. The compound MT-2 was to be measured. The compoundto be measured (the second material) and the compound TH-2 wereco-deposited on a quartz substrate to prepare a sample sealed in an NMRtube. It should be noted that the sample was prepared under thefollowing conditions: quartz substrate/TH-2: second material (filmthickness: 100 nm, concentration of second material: 12 mass %).

A phosphorescence spectrum (ordinate axis: phosphorescent luminousintensity, abscissa axis: wavelength) of the measurement sample wasmeasured at a low temperature (77 [K]), a tangent was drawn at the riseof the phosphorescence spectrum on the short-wavelength side, and anenergy amount calculated by the following conversion equation 2 based ona wavelength value λ_(edge)[nm] of an intersection between the tangentand the abscissa axis was defined as the energy gap Eg_(77K) at 77 [K].

Eg _(77K) [eV]=1239.85/λ_(edge)  Conversion Equation 2:

For phosphorescence measurement, a spectrophotofluorometer body F-4500(manufactured by Hitachi High-Technologies Corporation) was used.

The tangent to the rise of the phosphorescence spectrum on theshort-wavelength side was drawn as follows. While moving on a curve ofthe phosphorescence spectrum from the short-wavelength side to themaximum spectral value closest to the short-wavelength side among themaximum spectral values, a tangent was checked at each point on thecurve toward the long-wavelength of the phosphorescence spectrum. Aninclination of the tangent was increased as the curve rose (i.e., avalue of the ordinate axis was increased). A tangent drawn at a point ofthe maximum inclination (i.e., a tangent at an inflection point) wasdefined as the tangent to the rise of the phosphorescence spectrum onthe short-wavelength side.

The maximum with peak intensity being 15% or less of the maximum peakintensity of the spectrum was not included in the above-mentionedmaximum closest to the short-wavelength side of the spectrum. Thetangent drawn at a point of the maximum spectral value being the closestto the short-wavelength side and having the maximum inclination wasdefined as a tangent to the rise of the phosphorescence spectrum on theshort-wavelength side.

For phosphorescence measurement, a spectrophotofluorometer body F-4500(manufactured by Hitachi High-Technologies Corporation) was used.

Ionization Potential

A photoelectron spectroscopy device (AC-3, manufactured by Riken KeikiCo., Ltd.) was used for the measurement of an ionization potential underatmosphere. Specifically, a compound to be measured was irradiated withlight and the amount of electrons generated by charge separation wasmeasured.

Affinity (Electron Affinity)

The electron affinity was calculated by the following numerical formulafrom the measurement values of the ionization potential Ip and singletenergy EgS of the compound measured in the above manner.

Af=Ip−EgS

Delayed Fluorescence

Occurrence of delayed fluorescence emission was determined by measuringtransient photoluminescence (PL) using a device shown in FIG. 2 . Asample was prepared by co-depositing the compounds MT-2 and TH-2 on aquartz substrate at a ratio of the compound MT-2 of 12 mass % to form a100-nm-thick thin film.

Delayed fluorescence emission can be obtained using the device shown inFIG. 2 . There are two types of emission: Prompt emission observedimmediately when the excited state is achieved by exciting the compoundMT-2 with a pulse beam (i.e., a beam emitted from a pulse laser) havingan absorbable wavelength; and Delay emission observed not immediatelywhen but after the excited state is achieved. In Examples, occurrence ofdelayed fluorescence emission is determined when the amount of Delayemission is 5% or more relative to the amount of Prompt emission. Theamount of Delay emission of the compound MT-2 has been found to be 5% ormore relative to the amount of Prompt emission.

The amount of Prompt emission and the amount of Delay emission can beobtained in the same method as a method described in “Nature 492,234-238, 2012.” It should be noted that the amount of Prompt emissionand the amount of Delay emission may be calculated using a devicedifferent from the device shown in FIG. 2 and the device described inReference Literature 1.

TABLE 5 Singlet Energy Gap Ionization Affinity Energy Eg_(77K) PotentialAf Compound EgS [eV] [eV] Ip [eV] [eV] MT-1 2.58 1.80 — — MT-2 2.91 2.725.68 2.77 MT-3 3.55 2.92 6.45 2.90

Preparation and Evaluation of Organic EL Device

The organic EL device was manufactured and evaluated as follows.

Example 1

A glass substrate (size: 25 mm×75 mm×1.1 mm thick, manufactured byGeomatec Co., Ltd.) having an ITO transparent electrode (anode) wasultrasonic-cleaned in isopropyl alcohol for five minutes, and thenUV/ozone-cleaned for 30 minutes. A film of ITO was 130-nm thick.

After the glass substrate having the transparent electrode line wascleaned, the glass substrate was mounted on a substrate holder of avacuum evaporation apparatus. Initially, a compound HI wasvapor-deposited on a surface of the glass substrate where thetransparent electrode line was provided in a manner to cover thetransparent electrode, thereby forming a 5-nm-thick hole injectinglayer.

Subsequently, the compound HT-1 was vapor-deposited on the holeinjecting layer to form an 80-nm-thick first hole transporting layer onthe HI film.

Next, the compound HT-2 was vapor-deposited on the first holetransporting layer to form a 15-nm-thick second hole transporting layer.

Further, on the second hole transporting layer, the compound MT-1 (thefirst material), the compound MT-2 (the second material) and thecompound MT-3 (the third material) were co-deposited to form a25-nm-thick emitting layer. In the emitting layer, the respectiveconcentrations of the compounds MT-1, MT-2 and MT-3 were 1 mass %, 50mass % and 49 mass %.

The compound HB-1 was then vapor-deposited on the emitting layer to forma 5-nm-thick blocking layer.

The compound ET-1 was then vapor-deposited on the blocking layer to forma 20-nm-thick electron transporting layer.

Lithium fluoride (LiF) was then vapor-deposited on the electrontransporting layer to form a 1-nm-thick electron injecting electrode(cathode).

A metal aluminum (Al) was then vapor-deposited on the electron injectingelectrode to form an 80-nm-thick metal Al cathode.

A device arrangement of the organic EL device of Example 1 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(80)/HT-2(15)/MT-1: MT-2: MT-3(25, 1%: 50%:49%)/HB-1(5)/ET-1(20)/LiF(1)/A1(80)

Numerals in parentheses represent a film thickness (unit: nm). Thenumerals in the form of percentage in parentheses indicate ratios (mass%) of the materials in the emitting layer.

Comparative Example 1

An organic EL device of Comparative Example 1 was manufactured in thesame manner as the organic EL device of Example 1 except that theorganic EL device included a 20-nm-thick emitting layer prepared byco-depositing the compound MT-1 (the first material) and the compoundMT-2 (the second material) in place of the emitting layer of Example 1.In the emitting layer of the organic EL device of Comparative Example 1,the respective concentrations of the compounds MT-1 and MT-2 were 1 mass% and 99 mass %.

A device arrangement of the organic EL device of Comparative Example 1is roughly shown as follows.

ITO(130)/HI(5)/HT-1(80)/HT-2(15)/MT-1: MT-2(25, 1%:99%)/HB-1(5)/ET-1(20)/LiF(1)/A1(80)

Evaluation of Organic EL Devices

The manufactured organic EL devices of Example 1 and Comparative Example1 were evaluated as follows. The results are shown in Table 6.

Drive Voltage

Voltage was applied between the ITO transparent electrode and the metalA1 cathode such that the current density was 0.1 mA/cm², 1 mA/cm² or 10mA/cm², where voltage (unit: V) was measured.

Luminance and CIE1931 Chromaticity

Voltage was applied on each of the organic EL devices such that thecurrent density was 0.1 mA/cm², 1 mA/cm² or 10 mA/cm², where luminanceand CIE1931 chromaticity coordinates (x, y) were measured using aspectroradiometer CS-1000 (manufactured by Konica Minolta, Inc.).

Current Efficiency L/J and Electrical Power Efficiency η

Voltage was applied on each of the organic EL devices such that thecurrent density was 0.1 mA/cm², 1 mA/cm² or 10 mA/cm², where spectralradiance spectra were measured by the aforementioned spectroradiometer.Based on the obtained spectral radiance spectra, the current efficiency(unit: cd/A) and the electrical power efficiency η (unit: lm/W) werecalculated.

Main Peak Wavelength λ_(p)

A main peak wavelength λ_(p) was calculated based on the obtainedspectral-radiance spectra.

External Quantum Efficiency EQE

Voltage was applied on each of the organic EL devices such that thecurrent density was 0.1 mA/cm², 1 mA/cm² or 10 mA/cm², wherespectral-radiance spectra were measured using the abovespectroradiometer. The external quantum efficiency EQE (unit: %) wascalculated based on the obtained spectral-radiance spectra, assumingthat the spectra were provided under a Lambertian radiation.

TABLE 6 Current Density Voltage Luminance Chromaticity Chromaticity λ pL/J η EQE [mA/cm²] [V] [cd/m²] x y [nm] [cd/A] [lm/W] [%] Ex. 1  0.102.75 26.9  0.183 0.366 485 26.92 30.80 12.21  1.00 3.13 228.1  0.1780.354 484 22.81 22.91 10.58 10   3.83 1654.3   0.173 0.337 484 16.5413.56  7.93 Comp. 1  0.10 2.47 10.2  0.186 0.401 487 10.18 12.93  4.41 1.00 2.64 127.2  0.182 0.394 487 12.72 15.13  5.58 10   3.16 1297.7  0.178 0.386 485 12.98 12.90  5.77

As shown in Table 6, the organic EL device of Example 1 exhibited highcurrent efficiency L/J, electrical power efficiency η and externalquantum efficiency EQE irrespective of a current density for driving theorganic EL device as compared with the organic EL device of ComparativeExample 1. Supposedly, since the organic EL device of ComparativeExample 1 included the emitting layer consisting solely of the first and15 second materials, the luminous efficiency thereof was lowered. Theorganic EL device of Example 1 included the emitting layer containingthe third material in addition to the first and second materials, whichsupposedly results in improvement in luminous efficiency as comparedwith that of Comparative Example 1. Further, the organic EL device ofExample 1 emitted light with a short wavelength as compared withComparative Example 1, and emission of a strong-blue light from theorganic EL device of Example 1 was observed. This is supposedlyattributed to dispersion of the second material. As described above,Example 1 could provide a highly efficient blue-emitting organic ELdevice.

Next, other organic EL devices were manufactured using the followingcompounds as well as the compounds used in the above Example andComparative Example.

Evaluation of Compounds

Next, properties of the compounds MT-4 to MT-13 were measured. Ameasurement method and a calculation method are described below.Measurement results and calculation results are shown in Table 7. Themeasurement method and calculation method were the same as the above.The compounds MT-9 and MT-12 were each a delayed fluorescent compoundwith the amount of Delay emission of 5% or more relative to that ofPrompt emission.

TABLE 7 Singlet Energy Gap Ionization Affinity Energy Eg77K Potential AfCompound EgS [eV] [eV] Ip [eV] [eV] MT-4  3.54 3.03 6.04 2.50 MT-5  3.762.95 6.33 2.57 MT-6  3.53 3.06 6.20 2.67 MT-7  3.41 2.73 5.58 2.17 MT-8 3.59 2.74 6.10 2.51 MT-9  2.57 2.46 5.64 3.07 MT-10 2.23 — 5.37 3.14MT-11 2.28 — 5.61 3.33 MT-12 2.62 2.46 5.91 3.29 MT-13 3.74 2.85 6.152.41

Example 2

A glass substrate (size: 25 mm×75 mm×1.1 mm thick, manufactured byGeomatec Co., Ltd.) having an ITO transparent electrode (anode) wasultrasonic-cleaned in isopropyl alcohol for five minutes, and thenUV/ozone-cleaned for 30 minutes. A film of ITO was 70-nm thick.

After the glass substrate having the transparent electrode line wascleaned, the glass substrate was mounted on a substrate holder of avacuum evaporation apparatus. Initially, a compound HI wasvapor-deposited on a surface of the glass substrate where thetransparent electrode line was provided in a manner to cover thetransparent electrode, thereby forming a 5-nm-thick hole injectinglayer.

Subsequently, the compound HT-1 was vapor-deposited on the holeinjecting layer to form a 65-nm-thick first hole transporting layer onthe HI film.

The compound HT-2 was then vapor-deposited on the first holetransporting layer to form a 10-nm-thick second hole transporting layer.

Further, on the second hole transporting layer, the compounds MT-4, MT-9and MT-10 were co-deposited to form a 25-nm-thick emitting layer. In theemitting layer, the respective concentration of the compounds MT-10,MT-9 and MT-4 were 1 mass %, 50 mass % and 49 mass %.

The compound HB-2 was then vapor-deposited on the emitting layer to forma 5-nm-thick blocking layer.

The compound ET-1 was then vapor-deposited on the blocking layer to forma 30-nm-thick electron transporting layer.

Lithium fluoride (LiF) was then vapor-deposited on the electrontransporting layer to form a 1-nm-thick electron injecting electrode(cathode).

A metal aluminum (Al) was then vapor-deposited on the electron injectingelectrode to form an 80-nm-thick metal Al cathode.

A device arrangement of the organic EL device of Example 2 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-4: MT-9: MT-10(25, 49%: 50%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Example 3

An organic EL device of Example 3 was manufactured in the same manner asthe organic EL device of Example 2 except that the compound MT-6 wasused in place of the compound MT-4 in the emitting layer of Example 2. Adevice arrangement of the organic EL device of Example 3 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-6: MT-9: MT-10(25, 49%: 50%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Example 4

An organic EL device of Example 4 was manufactured in the same manner asthe organic EL device of Example 2 except that the compound MT-5 wasused in place of the compound MT-4 in the emitting layer of Example 2. Adevice arrangement of the organic EL device of Example 4 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-5: MT-9: MT-10(25, 49%: 50%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Example 5

An organic EL device of Example 5 was manufactured in the same manner asthe organic EL device of Example 2 except that the compound MT-7 wasused in place of the compound MT-4 in the emitting layer of Example 2. Adevice arrangement of the organic EL device of Example 5 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-7: MT-9: MT-10(25, 49%: 50%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Example 6

An organic EL device of Example 6 was manufactured in the same manner asthe organic EL device of Example 2 except that the compound MT-8 wasused in place of the compound MT-4 in the emitting layer of Example 2. Adevice arrangement of the organic EL device of Example 6 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-8: MT-9: MT-10(25, 49%: 50%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Comparative Example 2

An organic EL device of Comparative Example 2 was manufactured in thesame manner as the organic EL device of Example 2 except that theorganic EL device included a 25-nm-thick emitting layer prepared byco-depositing the compounds MT-9 and MT-10 in place of the emittinglayer of Example 2. In the emitting layer of the organic EL device ofComparative Example 2, the respective concentrations of the compoundsMT-10 and MT-9 were 1 mass % and 99 mass %. A device arrangement of theorganic EL device of Comparative Example 2 is roughly shown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-9: MT-10(25, 99%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Evaluation of Organic EL Devices

The manufactured organic EL devices of Examples 2 to 6 and Comparative 2were evaluated in the same manner as described above. Evaluation itemswere drive voltage, luminance, CIE1931 chromaticity, current efficiencyL/J, electrical power efficiency η, main peak wavelength λp and externalquantum efficiency EQE. The results are shown in Table 8.

TABLE 8 Current Voltage Density Luminance Chromaticity Chromaticity L/Jη EQE λ p [V] [mA/cm²] [cd/m²] x y [cd/A] [lm/W] [%] [nm] Ex. 2 3.76 106138.6 0.466 0.525 61.39 51.25 18.69 560 Ex. 3 3.46 10 6557.7 0.4690.523 65.58 59.46 20.11 561 Ex. 4 3.47 10 6647.7 0.466 0.525 66.48 60.2320.36 561 Ex. 5 2.96 10 6749.7 0.465 0.527 67.50 71.67 20.67 560 Ex. 63.24 10 5953.7 0.470 0.523 59.54 57.79 18.49 561 Comp. 2 2.94 10 4855.30.476 0.519 48.55 51.81 14.99 561

As shown in Table 8, the organic EL devices of Examples 2 to 6 werehigher in luminous efficiency than the organic EL device of ComparativeExample 2. The organic EL device of Comparative Example 2 included theemitting layer consisting solely of the compounds MT-9 and MT-10. Ascompared with the organic EL device of Comparative Example 2, theorganic EL devices of Examples 2 to 6 each included the emitting layerfurther containing the third material. Specifically, the emitting layersof Examples 2 to 6 respectively contained the compounds MT-4, MT-6,MT-5, MT-7 and MT-8 as the third material. Consequently, the organic ELdevices of Examples 2 to 6 were higher in current efficiency andexternal quantum efficiency than the organic EL device of ComparativeExample 2.

Example 7

An organic EL device of Example 7 was manufactured in the same manner asthe organic EL device of Example 2 except that the compound HB-3 wasused in place of the compound HB-2 in the blocking layer of Example 2. Adevice arrangement of the organic EL device of Example 7 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-4: MT-9: MT-10(25, 49%: 50%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Example 8

An organic EL device of Example 8 was manufactured in the same manner asthe organic EL device of Example 7 except that the compound MT-6 wasused in place of the compound MT-4 in the emitting layer of Example 7. Adevice arrangement of the organic EL device of Example 8 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-6: MT-9: MT-10(25, 49%: 50%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Example 9

An organic EL device of Example 9 was manufactured in the same manner asthe organic EL device of Example 7 except that the compound MT-5 wasused in place of the compound MT-4 in the emitting layer of Example 7. Adevice arrangement of the organic EL device of Example 9 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-5: MT-9: MT-10(25, 49%: 50%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Example 10

An organic EL device of Example 10 was manufactured in the same manneras the organic EL device of Example 7 except that the compound MT-7 wasused in place of the compound MT-4 in the emitting layer of Example 7. Adevice arrangement of the organic EL device of Example 10 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-7: MT-9: MT-10(25, 49%: 50%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Example 11

An organic EL device of Example 11 was manufactured in the same manneras the organic EL device of Example 7 except that the compound MT-8 wasused in place of the compound MT-4 in the emitting layer of Example 7. Adevice arrangement of the organic EL device of Example 11 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-8: MT-9: MT-10(25, 49%: 50%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Comparative Example 3

An organic EL device of Comparative Example 3 was manufactured in thesame manner as the organic EL device of Example 7 except that theorganic EL device included a 25-nm-thick emitting layer prepared byco-depositing the compounds MT-9 and MT-10 in place of the emittinglayer of Example 7. In the emitting layer of the organic EL device ofComparative Example 3, the respective concentrations of the compoundsMT-10 and MT-9 were 1 mass % and 99 mass %. A device arrangement of theorganic EL device of Comparative Example 3 is roughly shown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-9: MT-10(25, 99%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Evaluation of Organic EL Devices

The manufactured organic EL devices of Examples 7 to 11 and ComparativeExample 3 were evaluated in the same manner as described above.Evaluation items were drive voltage, luminance, CIE1931 chromaticity,current efficiency L/J, electrical power efficiency η, main peakwavelength λp and external quantum efficiency EQE. The results are shownin Table 9.

TABLE 9 Current Voltage Density Luminance Chromaticity Chromaticity L/Jη EQE λ p [V] [mA/cm²] [cd/m²] x y [cd/A] [lm/W] [%] [nm] Ex. 7  3.79 105909.6 0.464 0.527 59.10 48.97 18.00 561 Ex. 8  3.49 10 6182.2 0.4660.525 61.82 55.67 18.88 561 Ex. 9  3.46 10 6936.5 0.466 0.526 69.3663.06 21.18 560 Ex. 10 2.99 10 6700.3 0.464 0.528 67.00 70.31 20.50 560Ex. 11 3.26 10 5966.1 0.469 0.524 59.66 57.43 18.50 561 Comp. 3 2.99 104920.1 0.475 0.519 49.20 51.74 15.16 562

As shown in Table 9, the organic EL devices of Examples 7 to 11 werehigher in luminous efficiency than the organic EL device of ComparativeExample 3. The organic EL device of Comparative Example 3 included theemitting layer consisting solely of the compounds MT-9 and MT-10. Ascompared with the organic EL device of Comparative Example 3, theorganic EL devices of Examples 7 to 11 each included the emitting layerfurther containing the third material. Specifically, the emitting layersof Examples 7 to 11 respectively contained the compounds MT-4, MT-6,MT-5, MT-7 and MT-8 as the third material. Consequently, the organic ELdevices of Examples 7 to 11 were higher in current efficiency andexternal quantum efficiency than the organic EL device of ComparativeExample 3.

Example 12

An organic EL device of Example 12 was manufactured in the same manneras the organic EL device of Example 2 except that the compound MT-11 wasused in place of the compound MT-10 in the emitting layer of Example 2.A device arrangement of the organic EL device of Example 12 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-4: MT-9: MT-11(25, 49%: 50%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Example 13

An organic EL device of Example 13 was manufactured in the same manneras the organic EL device of Example 12 except that the compound MT-6 wasused in place of the compound MT-4 in the emitting layer of Example 12.A device arrangement of the organic EL device of Example 13 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-6: MT-9: MT-11(25, 49%: 50%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Example 14

An organic EL device of Example 14 was manufactured in the same manneras the organic EL device of Example 12 except that the compound MT-7 wasused in place of the compound MT-4 in the emitting layer of Example 12.A device arrangement of the organic EL device of Example 14 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-7: MT-9: MT-11(25, 49%: 50%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Example 15

An organic EL device of Example 15 was manufactured in the same manneras the organic EL device of Example 12 except that the compound MT-8 wasused in place of the compound MT-4 in the emitting layer of Example 12.A device arrangement of the organic EL device of Example 15 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-8: MT-9: MT-11(25, 49%: 50%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Comparative Example 4

An organic EL device of Comparative Example 4 was manufactured in thesame manner as the organic EL device of Example 12 except that theorganic EL device included a 25-nm-thick emitting layer prepared byco-depositing the compounds MT-9 and MT-11 in place of the emittinglayer of Example 12. In the emitting layer of the organic EL device ofComparative Example 4, the respective concentrations of the compoundsMT-11 and MT-9 were 1 mass % and 99 mass %. A device arrangement of theorganic EL device of Comparative Example 4 is roughly shown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-9: MT-11(25, 99%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Evaluation of Organic EL Devices

The manufactured organic EL devices of Examples 12 to 15 and ComparativeExample 4 were evaluated in the same manner as described above.Evaluation items were drive voltage, luminance, CIE1931 chromaticity,current efficiency L/J, electrical power efficiency η, main peakwavelength λp and external quantum efficiency EQE. The results are shownin Table 10.

TABLE 10 Current Voltage Density Luminance Chromaticity Chromaticity L/Jη EQE λ p [V] [mA/cm²] [cd/m²] x y [cd/A] [lm/W] [%] [nm] Ex. 12 4.02 105438.6 0.451 0.538 54.39 42.53 16.46 558 Ex. 13 3.36 10 6290.3 0.4520.538 62.90 58.76 18.97 559 Ex. 14 3.06 10 6060.6 0.455 0.536 60.6162.25 18.52 560 Ex. 15 3.29 10 5020.2 0.465 0.527 50.20 47.91 15.66 562Comp. 4 3.07 10 4380.9 0.466 0.527 43.81 44.84 13.43 560

As shown in Table 10, the organic EL devices of Examples 12 to 15 werehigher in luminous efficiency than the organic EL device of ComparativeExample 4. The organic EL device of Comparative Example 4 included theemitting layer consisting solely of the compounds MT-9 and MT-11. Ascompared with the organic EL device of Comparative Example 4, theorganic EL devices of Examples 12 to 15 each included the emitting layerfurther containing the third material. Specifically, the emitting layersof Examples 12 to 15 respectively contained the compounds MT-4, MT-6,MT-7 and MT-8 as the third material. Consequently, the organic ELdevices of Examples 12 to 15 were higher in current efficiency andexternal quantum efficiency than the organic EL device of ComparativeExample 4.

Example 16

An organic EL device of Example 16 was manufactured in the same manneras the organic EL device of Example 12 except that the compound HB-3 wasused in place of the compound HB-2 in the blocking layer in Example 12.A device arrangement of the organic EL device of Example 16 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-4: MT-9: MT-11(25, 49%: 50%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Example 17

An organic EL device of Example 17 was manufactured in the same manneras the organic EL device of Example 16 except that the compound MT-6 wasused in place of the compound MT-4 in the emitting layer of Example 16.A device arrangement of the organic EL device of Example 17 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-6: MT-9: MT-11(25, 49%: 50%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Example 18

An organic EL device of Example 18 was manufactured in the same manneras the organic EL device of Example 16 except that the compound MT-7 wasused in place of the compound MT-4 in the emitting layer of Example 16.A device arrangement of the organic EL device of Example 18 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-7: MT-9: MT-11(25, 49%: 50%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Example 19

An organic EL device of Example 19 was manufactured in the same manneras the organic EL device of Example 16 except that the compound MT-8 wasused in place of the compound MT-4 in the emitting layer of Example 16.A device arrangement of the organic EL device of Example 19 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-8: MT-9: MT-11(25, 49%: 50%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Comparative Example 5

An organic EL device of Comparative Example 5 was manufactured in thesame manner as the organic EL device of Example 16 except that theorganic EL device included a 25-nm-thick emitting layer prepared byco-depositing the compounds MT-9 and MT-11 in place of the emittinglayer of Example 16. In the emitting layer of the organic EL device ofComparative Example 5, the respective concentrations of the compoundsMT-11 and MT-9 were 1 mass % and 99 mass %. A device arrangement of theorganic EL device of Comparative Example 5 is roughly shown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(10)/MT-9: MT-11(25, 99%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Evaluation of Organic EL Devices

The manufactured organic EL devices of Examples 16 to 19 and ComparativeExample 5 were evaluated in the same manner as described above.Evaluation items were drive voltage, luminance, CIE1931 chromaticity,current efficiency L/J, electrical power efficiency η, main peakwavelength λp and external quantum efficiency EQE. The results are shownin Table 11.

TABLE 11 Current Voltage Density Luminance Chromaticity Chromaticity L/Jη EQE λ p [V] [mA/cm²] [cd/m²] x y [cd/A] [lm/W] [%] [nm] Ex. 16 4.09 105215.5 0.452 0.537 52.15 40.08 15.81 559 Ex. 17 3.39 10 6310.3 0.4520.537 63.10 58.48 19.06 559 Ex. 18 3.09 10 6136.5 0.454 0.537 61.3662.49 18.76 559 Ex. 19 3.33 10 5234.3 0.463 0.529 52.34 49.45 16.31 562Comp. 5 3.16 10 4455.9 0.464 0.529 44.56 44.36 13.61 560

As shown in Table 11, the organic EL devices of Examples 16 to 19 werehigher in luminous efficiency than the organic EL device of ComparativeExample 5. The organic EL device of Comparative Example 5 included theemitting layer consisting solely of the compounds MT-9 and MT-11. Ascompared with the organic EL device of Comparative Example 5, theorganic EL devices of Examples 16 to 19 each included the emitting layerfurther containing the third material. Specifically, the emitting layersof Examples 16 to 19 respectively contained the compounds MT-4, MT-6,MT-7 and MT-8 as the third material. Consequently, the organic ELdevices of Examples 16 to 19 were higher in current efficiency andexternal quantum efficiency than the organic EL device of ComparativeExample 5.

Example 20

A glass substrate (size: 25 mm×75 mm×1.1 mm thick, manufactured byGeomatec Co., Ltd.) having an ITO transparent electrode (anode) wasultrasonic-cleaned in isopropyl alcohol for five minutes, and thenUV/ozone-cleaned for 30 minutes. A film of ITO was 70-nm thick.

After the glass substrate having the transparent electrode line wascleaned, the glass substrate was mounted on a substrate holder of avacuum evaporation apparatus. Initially, a compound HI wasvapor-deposited on a surface of the glass substrate where thetransparent electrode line was provided in a manner to cover thetransparent electrode, thereby forming a 5-nm-thick hole injectinglayer.

Subsequently, the compound HT-1 was vapor-deposited on the holeinjecting layer to form a 65-nm-thick first hole transporting layer onthe HI film.

Next, the compound HT-2 was vapor-deposited on the first holetransporting layer to form a 5-nm-thick second hole transporting layer.

Further, the compound CBP was vapor-deposited on the second holetransporting layer to form a 5-nm-thick first blocking layer.

The compounds MT-13, MT-12 and MT-10 were then co-deposited on the firstblocking layer to form a 25-nm-thick emitting layer. In the emittinglayer, the respective concentration of the compounds MT-10, MT-12 andMT-13 were 1 mass %, 50 mass % and 49 mass %.

The compound HB-2 was then vapor-deposited on the emitting layer to forma 5-nm-thick second blocking layer.

The compound ET-1 was then vapor-deposited on the second blocking layerto form a 30-nm-thick electron transporting layer.

Lithium fluoride (LiF) was then vapor-deposited on the electrontransporting layer to form a 1-nm-thick electron injecting electrode(cathode).

A metal aluminum (Al) was then vapor-deposited on the electron injectingelectrode to form an 80-nm-thick metal Al cathode.

A device arrangement of the organic EL device of Example 20 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(5)/CBP(5)/MT-13: MT-12: MT-10(25, 49%: 50%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Example 21

An organic EL device of Comparative Example 21 was manufactured in thesame manner as the organic EL device of Example 20 except that theconcentrations of the compounds MT-10, MT-12 and MT-13 contained in theemitting layer of Example 20 were respectively changed to 1 mass %, 25mass % and 74 mass %. A device arrangement of the organic EL device ofExample 21 is roughly shown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(5)/CBP(5)/MT-13: MT-12: MT-10(25, 74%: 25%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Example 22

An organic EL device of Comparative Example 22 was manufactured in thesame manner as the organic EL device of Example 20 except that thecompound MT-5 was used in place of the compound MT-13 in the emittinglayer of Example 20, and the concentrations of the compounds MT-10,MT-12 and MT-5 contained in the emitting layer were respectively changedto 1 mass %, 24 mass % and 75 mass %. A device arrangement of theorganic EL device of Example 22 is roughly shown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(5)/CBP(5)/MT-5: MT-12: MT-10(25, 75%: 24%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Comparative Example 6

An organic EL device of Comparative Example 6 was manufactured in thesame manner as the organic EL device of Example 20 except that theorganic EL device included a 25-nm-thick emitting layer prepared byco-depositing the compounds MT-12 and MT-10 in place of the emittinglayer of Example 20. In the emitting layer of the organic EL device ofComparative Example 6, the respective concentrations of the compoundsMT-10 and MT-12 were 1 mass % and 99 mass %. A device arrangement of theorganic EL device of Comparative Example 6 is roughly shown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(5)/CBP(5)/MT-12: MT-10(25, 99%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Evaluation of Organic EL Devices

The manufactured organic EL devices of Examples 20 to 22 and ComparativeExample 6 were evaluated in the same manner as described above.Evaluation items were drive voltage, luminance, CIE1931 chromaticity,current efficiency L/J, electrical power efficiency η, main peakwavelength λp and external quantum efficiency EQE. The results are shownin Table 12.

TABLE 12 Current Voltage Density Luminance Chromaticity Chromaticity L/Jη EQE λ p [V] [mA/cm²] [cd/m²] x y [cd/A] [lm/W] [%] [nm] Ex. 20 4.14 103775.5 0.423 0.556 37.76 28.62 11.12 555 Ex. 21 4.67 10 4582.5 0.4100.561 45.82 30.85 13.32 554 Ex. 22 4.72 10 4892.1 0.406 0.563 48.9232.55 14.20 553 Comp. 6 4.00 10 1950.7 0.460 0.529 19.51 15.33  6.13 562

As shown in Table 12, the organic EL devices of Examples 20 to 22 werehigher in luminous efficiency than the organic EL device of ComparativeExample 6. The organic EL device of Comparative Example 6 included theemitting layer consisting solely of the compounds MT-10 and MT-12. Ascompared with the organic EL device of Comparative Example 6, theorganic EL devices of Examples 20 to 22 each included the emitting layerfurther containing the third material. Specifically, the emitting layersof Examples 20 and 21 each contained the compound MT-13 as the thirdmaterial, and the emitting layer of Example 22 contained MT-5 as thethird material. Consequently, the organic EL devices of Examples 20 to22 were higher in current efficiency, electrical power efficiency andexternal quantum efficiency than the organic EL device of ComparativeExample 6.

Example 23

An organic EL device of Example 23 was manufactured in the same manneras the organic EL device of Example 20 except that the compound HB-3 wasused in place of the compound HB-2 in the blocking layer of Example 20.A device arrangement of the organic EL device of Example 23 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(5)/CBP(5)/MT-13: MT-12: MT-10(25, 49%: 50%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Example 24

An organic EL device of Comparative Example 24 was manufactured in thesame manner as the organic EL device of Example 23 except that theconcentrations of the compounds MT-10, MT-12 and MT-13 contained in theemitting layer of Example 23 were respectively changed to 1 mass %, 25mass % and 74 mass %. A device arrangement of the organic EL device ofExample 24 is roughly shown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(5)/CBP(5)/MT-13: MT-12: MT-10(25, 74%: 25%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Example 25

An organic EL device of Comparative Example 25 was manufactured in thesame manner as the organic EL device of Example 23 except that thecompound MT-5 was used in place of the compound MT-13 in the emittinglayer of Example 23, and the concentrations of the compounds MT-10,MT-12 and MT-5 contained in the emitting layer were respectively changedto 1 mass %, 24 mass % and 75 mass %. A device arrangement of theorganic EL device of Example 25 is roughly shown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(5)/CBP(5)/MT-5: MT-12: MT-10(25, 75%: 24%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Comparative Example 7

An organic EL device of Comparative Example 7 was manufactured in thesame manner as the organic EL device of Example 23 except that theorganic EL device included a 25-nm-thick emitting layer prepared byco-depositing the compounds MT-12 and MT-10 in place of the emittinglayer of Example 23. In the emitting layer of the organic EL device ofComparative Example 7, the respective concentrations of the compoundsMT-10 and MT-12 were 1 mass % and 99 mass %. A device arrangement of theorganic EL device of Comparative Example 7 is roughly shown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(5)/CBP(5)/MT-12: MT-10(25, 99%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Evaluation of Organic EL Devices

The manufactured organic EL devices of Examples 23 to 25 and ComparativeExample 7 were evaluated in the same manner as described above.Evaluation items were drive voltage, luminance, CIE1931 chromaticity,current efficiency L/J, electrical power efficiency η, main peakwavelength λp and external quantum efficiency EQE. The results are shownin Table 13.

TABLE 13 Current Voltage Density Luminance Chromaticity Chromaticity L/Jη EQE λ p [V] [mA/cm²] [cd/m²] x y [cd/A] [lm/W] [%] [nm] Ex. 22 4.11 103695.1 0.421 0.556 36.95 28.23 10.90 555 Ex. 23 4.65 10 4445.8 0.4060.559 44.46 30.01 12.96 553 Ex. 24 4.70 10 5009.2 0.402 0.559 50.0933.47 14.59 553 Comp. 7 4.00 10 2013.4 0.457 0.531 20.13 15.83  6.29 560

As shown in Table 13, the organic EL devices of Examples 23 to 25 werehigher in luminous efficiency than the organic EL device of ComparativeExample 7. The organic EL device of Comparative Example 7 included theemitting layer consisting solely of the compounds MT-10 and MT-12. Ascompared with the organic EL device of Comparative Example 7, theorganic EL devices of Examples 23 to 25 each included the emitting layerfurther containing the third material. Specifically, the emitting layersof Examples 23 and 24 each contained the compound MT-13 as the thirdmaterial, and the emitting layer of Example 25 contained MT-5 as thethird material. Consequently, the organic EL devices of Examples 23 to25 were higher in current efficiency, electrical power efficiency andexternal quantum efficiency than the organic EL device of ComparativeExample 7.

Example 26

An organic EL device of Comparative Example 26 was manufactured in thesame manner as the organic EL device of Example 20 except that thecompound MT-11 was used in place of the compound MT-10 in the emittinglayer of Example 20, and the concentrations of the compounds MT-11,MT-12 and MT-13 contained in the emitting layer were respectivelychanged to 1 mass %, 25 mass % and 74 mass %. A device arrangement ofthe organic EL device of Example 26 is roughly shown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(5)/CBP(5)/MT-13: MT-12: MT-11(25, 74%: 25%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Comparative Example 8

An organic EL device of Comparative Example 8 was manufactured in thesame manner as the organic EL device of Example 26 except that theorganic EL device included a 25-nm-thick emitting layer prepared byco-depositing the compounds MT-12 and MT-11 in place of the emittinglayer of Example 26. In the emitting layer of the organic EL device ofComparative Example 8, the respective concentrations of the compoundsMT-11 and MT-12 were 1 mass % and 99 mass %. A device arrangement of theorganic EL device of Comparative Example 8 is roughly shown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(5)/CBP(5)/MT-12: MT-11(25, 99%:1%)/HB-2(5)/ET-1(30)/LiF(1)/Al(80)

Evaluation of Organic EL Devices

The manufactured organic EL devices of Example 26 and ComparativeExample 8 were evaluated in the same manner as described above.Evaluation items were drive voltage, luminance, CIE1931 chromaticity,current efficiency L/J, electrical power efficiency η, main peakwavelength λp and external quantum efficiency EQE. The results are shownin Table 14.

TABLE 14 Current Voltage Density Luminance Chromaticity Chromaticity L/Jη EQE λ p [V] [mA/cm²] [cd/m²] x y [cd/A] [lm/W] [%] [nm] Ex. 26 4.83 103817.5 0.439 0.543 38.18 24.84 11.38 559 Comp. 8 4.15 10 1649.0 0.4860.508 16.49 12.48  5.37 568

As shown in Table 14, the organic EL device of Example 26 was higher inluminous efficiency than the organic EL device of Comparative Example 8.The organic EL device of Comparative Example 8 included the emittinglayer consisting solely of the compounds MT-11 and MT-12. As comparedwith the organic EL device of Comparative Example 8, the organic ELdevice of Example 26 included the emitting layer further containing thethird material. Consequently, the organic EL device of Example 26 washigher in current efficiency, electrical power efficiency and externalquantum efficiency than the organic EL device of Comparative Example 8.

Example 27

An organic EL device of Example 27 was manufactured in the same manneras the organic EL device of Example 26 except that the compound HB-3 wasused in place of the compound HB-2 in the blocking layer of Example 26.A device arrangement of the organic EL device of Example 27 is roughlyshown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(5)/CBP(5)/MT-13: MT-12: MT-11(25, 74%: 25%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Comparative Example 9

An organic EL device of Comparative Example 9 was manufactured in thesame manner as the organic EL device of Example 27 except that theorganic EL device included a 25-nm-thick emitting layer prepared byco-depositing the compounds MT-12 and MT-11 in place of the emittinglayer of Example 27. In the emitting layer of the organic EL device ofComparative Example 9, the respective concentrations of the compoundsMT-11 and MT-12 were 1 mass % and 99 mass %. A device arrangement of theorganic EL device of Comparative Example 9 is roughly shown as follows.

ITO(70)/HI(5)/HT-1(65)/HT-2(5)/CBP(5)/MT-12: MT-11(25, 99%:1%)/HB-3(5)/ET-1(30)/LiF(1)/Al(80)

Evaluation of Organic EL Devices

The manufactured organic EL devices of Example 27 and ComparativeExample 9 were evaluated in the same manner as described above.Evaluation items were drive voltage, luminance, CIE1931 chromaticity,current efficiency L/J, electrical power efficiency η, main peakwavelength λp and external quantum efficiency EQE. The results are shownin Table 15.

TABLE 15 Current Voltage Density Luminance Chromaticity Chromaticity L/Jη EQE λ p [V] [mA/cm²] [cd/m²] x y [cd/A] [lm/W] [%] [nm] Ex. 27 4.83 103919.6 0.437 0.543 39.20 25.51 11.67 559 Comp. 9 4.13 10 1679.2 0.4840.509 16.79 12.78  5.45 568

As shown in Table 15, the organic EL device of Example 27 was higher inluminous efficiency than the organic EL device of Comparative Example 9.The organic EL device of Comparative Example 9 included the emittinglayer consisting solely of the compounds MT-11 and MT-12. As comparedwith the organic EL device of Comparative Example 9, the organic ELdevice of Example 27 included the emitting layer further containing thethird material. Consequently, the organic EL device of Example 27 washigher in current efficiency, electrical power efficiency and externalquantum efficiency than the organic EL device of Comparative Example 9.

1: An organic electroluminescence device comprising: an anode; anemitting layer; and a cathode, the emitting layer comprising a firstmaterial, a second material and a third material, wherein the firstmaterial is a fluorescent material, the second material is a delayedfluorescent material, and the third material has a singlet energy largerthan a singlet energy of the second material and includes at least onegroup selected from the group consisting of a group of formula (30b-1),a group of formula (30c-1), a group of formula (30d-1), a group offormula (30e-1), a group of formula (30e-2), a group of formula (30g), agroup of formula (30h), and a group of formula (30i),

wherein X₃₁, X₃₄ and X₃₆ each independently represent a nitrogen atom orCR₃₁; Y₃₁, Y₃₂ and Y₃₅ to Y₃₈ each independently represent a nitrogenatom, CR₃₂ or a carbon atom bonded to another atom in the molecule ofthe third material; R₃₁ and R₃₂ each independently represent a hydrogenatom or a substituent, the substituent being selected from the groupconsisting of a halogen atom, cyano group, substituted or unsubstitutedalkyl group having 1 to 30 carbon atoms, substituted or unsubstitutedcycloalkyl group having 3 to 30 ring carbon atoms, substituted orunsubstituted trialkylsilyl group, substituted or unsubstitutedarylalkylsilyl group, substituted or unsubstituted triarylsilyl group,substituted or unsubstituted diaryl phosphine oxide group, substitutedor unsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms, and substituted or unsubstituted heterocyclic group having 5 to30 ring atoms, the substituted or unsubstituted aromatic hydrocarbongroup having 6 to 30 ring carbon atoms being a non-fused ring; Y₃₉represents NR₃₃, an oxygen atom or a sulfur atom, R₃₃ being asubstituent that is selected from the group consisting of a cyano group,substituted or unsubstituted alkyl group having 1 to 20 carbon atoms,substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbonatoms, substituted or unsubstituted alkoxy group having 1 to 20 carbonatoms, substituted or unsubstituted aryloxy group having 6 to 30 ringcarbon atoms, substituted or unsubstituted alkylthio group having 1 to20 carbon atoms, substituted or unsubstituted arylthio group having 6 to30 ring carbon atoms, substituted or unsubstituted alkylsilyl grouphaving 3 to 50 carbon atoms, substituted or unsubstituted arylsilylgroup having 6 to 50 ring carbon atoms, substituted or unsubstitutedaromatic hydrocarbon group having 6 to 30 ring carbon atoms, andsubstituted or unsubstituted heterocyclic group having 5 to 30 ringatoms, the substituted or unsubstituted aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms being a non-fused ring; Z₃₁ is anoxygen atom, sulfur atom or CR₅₁R₅₂ X₃₄ and Y₃₂ are optionallycross-linked via an oxygen atom, sulfur atom or CR₅₃R₅₄; R₅₁ to R₅₄ eachindependently represent the same as R₃₃ being the substituent; and awavy line shows a bonding position with another atom or anotherstructure in the molecule of the third material,

wherein X₃₁, X₃₄ and X₃₆ each independently represent a nitrogen atom orCR₃₁; Y₃₁, Y₃₂, Y₃₅, Y₃₇ and Y₃₈ each independently represent a nitrogenatom or CR₃₂; Y₄₁ to Y₄₅, Y₄₇ and Y₄₈ each independently represent anitrogen atom, CR₃₄ or a carbon atom bonded to another atom in themolecule of the third material; R₃₁, R₃₂ and R₃₄ each independentlyrepresent a hydrogen atom or a substituent, the substituent beingselected from the group consisting of a halogen atom, cyano group,substituted or unsubstituted alkyl group having 1 to 30 carbon atoms,substituted or unsubstituted cycloalkyl group having 3 to 30 ring carbonatoms, substituted or unsubstituted trialkylsilyl group, substituted orunsubstituted arylalkylsilyl group, substituted or unsubstitutedtriarylsilyl group, substituted or unsubstituted diaryl phosphine oxidegroup, substituted or unsubstituted aromatic hydrocarbon group having 6to 30 ring carbon atoms, and substituted or unsubstituted heterocyclicgroup having 5 to 30 ring atoms, the substituted or unsubstitutedaromatic hydrocarbon group having 6 to 30 ring carbon atoms being anon-fused ring; Y₃₉ represents NR₃₃, an oxygen atom or a sulfur atom;Y₄₉ represents NR₃₅, an oxygen atom or a sulfur atom; R₃₃ and R₃₅ eachindependently represent a substituent that is selected from the groupconsisting of a cyano group, substituted or unsubstituted alkyl grouphaving 1 to 20 carbon atoms, substituted or unsubstituted cycloalkylgroup having 3 to 20 ring carbon atoms, substituted or unsubstitutedalkoxy group having 1 to 20 carbon atoms, substituted or unsubstitutedaryloxy group having 6 to 30 ring carbon atoms, substituted orunsubstituted alkylthio group having 1 to 20 carbon atoms, substitutedor unsubstituted arylthio group having 6 to 30 ring carbon atoms,substituted or unsubstituted alkylsilyl group having 3 to 50 carbonatoms, substituted or unsubstituted arylsilyl group having 6 to 50 ringcarbon atoms, substituted or unsubstituted aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms, and substituted or unsubstitutedheterocyclic group having 5 to 30 ring atoms, the substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms being a non-fused ring; Z₃₂ is an oxygen atom, sulfur atom orCR₅₁R52; X₃₄ and Y₃₂ are optionally cross-linked via an oxygen atom,sulfur atom or CR₅₃R₅₄; R₅₁ to R₄ each independently represent the sameas R₃₃ and R₃₅ each being the substituent; and a wavy line(s) shows abonding position with another atom or another structure in the moleculeof the third material,

wherein X₃₁, X₃₄ and X₃₆ each independently represent a nitrogen atom orCR₃₁; X₄₃, X₄₄ and X₄₅ each independently represent a nitrogen atom orCR₃₆; R₃₁ and R₃₆ each independently represent a substituent that isselected from the group consisting of a halogen atom, cyano group,substituted or unsubstituted alkyl group having 1 to 30 carbon atoms,substituted or unsubstituted cycloalkyl group having 3 to 30 ring carbonatoms, substituted or unsubstituted trialkylsilyl group, substituted orunsubstituted arylalkylsilyl group, substituted or unsubstitutedtriarylsilyl group, substituted or unsubstituted diaryl phosphine oxidegroup, substituted or unsubstituted aromatic hydrocarbon group having 6to 30 ring carbon atoms, and substituted or unsubstituted heterocyclicgroup having 5 to 30 ring atoms, the substituted or unsubstitutedaromatic hydrocarbon group having 6 to 30 ring carbon atoms being anon-fused ring; Z₃₃ is an oxygen atom, sulfur atom or CR₅₅R₅₆; X₃₄ andX₄₅ are optionally cross-linked via an oxygen atom, sulfur atom orCR₅₇R₅₈; R₅₅ to R₅₈ each independently represent a substituent that isselected from the group consisting of a halogen atom, cyano group,substituted or unsubstituted alkyl group having 1 to 20 carbon atoms,substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbonatoms, substituted or unsubstituted alkoxy group having 1 to 20 carbonatoms, substituted or unsubstituted aryloxy group having 6 to 30 ringcarbon atoms, substituted or unsubstituted alkylthio group having 1 to20 carbon atoms, substituted or unsubstituted arylthio group having 6 to30 ring carbon atoms, substituted or unsubstituted alkylsilyl grouphaving 3 to 50 carbon atoms, substituted or unsubstituted arylsilylgroup having 6 to 50 ring carbon atoms, substituted or unsubstitutedaromatic hydrocarbon group having 6 to 30 ring carbon atoms, andsubstituted or unsubstituted heterocyclic group having 5 to 30 ringatoms, the substituted or unsubstituted aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms being a non-fused ring, and a wavyline(s) shows a bonding position with another atom or another structurein the molecule of the third material,

wherein X₃₁, X₃₂, X₃₄ and X₃₆ each independently represent a nitrogenatom or CR₃₁; X₄₃, X₄₄ and X₄₅ each independently represent a nitrogenatom or CR₃₆; Y₃₁ to Y₃₅, Y₃₇ and Y₃₈ each independently represent anitrogen atom, CR₃₂ or a carbon atom bonded to another atom in themolecule of the third material; Z₃₄ is an oxygen atom, sulfur atom orCR₅₅R₅₆; Z₃₅ is an oxygen atom, sulfur atom or CR₅₉R₆₀; R₃₁, R₃₂ and R₃₆each independently represent a hydrogen atom or a substituent, thesubstituent being selected from the group consisting of a halogen atom,cyano group, substituted or unsubstituted alkyl group having 1 to 30carbon atoms, substituted or unsubstituted cycloalkyl group having 3 to30 ring carbon atoms, substituted or unsubstituted trialkylsilyl group,substituted or unsubstituted arylalkylsilyl group, substituted orunsubstituted triarylsilyl group, substituted or unsubstituted diarylphosphine oxide group, substituted or unsubstituted aromatic hydrocarbongroup having 6 to 30 ring carbon atoms, and substituted or unsubstitutedheterocyclic group having 5 to 30 ring atoms, the substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms being a non-fused ring; Y₃₉ is NR₃₃, an oxygen atom or a sulfuratom: R₃₃ is a substituent that is selected from the group consisting ofa cyano group, substituted or unsubstituted alkyl group having 1 to 20carbon atoms, substituted or unsubstituted cycloalkyl group having 3 to20 ring carbon atoms, substituted or unsubstituted alkoxy group having 1to 20 carbon atoms, substituted or unsubstituted aryloxy group having 6to 30 ring carbon atoms, substituted or unsubstituted alkylthio grouphaving 1 to 20 carbon atoms, substituted or unsubstituted arylthio grouphaving 6 to 30 ring carbon atoms, substituted or unsubstitutedalkylsilyl group having 3 to 50 carbon atoms, substituted orunsubstituted arylsilyl group having 6 to 50 ring carbon atoms,substituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, and substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, the substituted or unsubstituted aromatichydrocarbon group having 6 to 30 ring carbon atoms being a non-fusedring; X₃₄ and X₄₅ are optionally cross-linked via an oxygen atom, sulfuratom or CR₅₇R₅₈; X₄₃ and Y₃₅ are optionally cross-linked via an oxygenatom, sulfur atom or CR₆₁R₆₂; and R₅₅ to R₆₂ each independentlyrepresent the same as R₃₃ being the substituent; and. a wavy line(s)shows a bonding position with another atom or another structure in themolecule of the third material,

wherein X₃₁, X₃₂, X₃₄ and X₃₆ each independently represent a nitrogenatom or CR₃₁; Y₃₁ to Y₃₈, Y₄₁ to Y₄₈ and Y₅₁ to Y₅₈ each independentlyrepresent a nitrogen atom, CR₃₇ or a carbon atom bonded to another atomin the molecule of the third material; R₃₁ and R₃₇ each independentlyrepresent a hydrogen atom or a substituent, the substituent beingselected from the group consisting of a halogen atom, cyano group,substituted or unsubstituted alkyl group having 1 to 30 carbon atoms,substituted or unsubstituted cycloalkyl group having 3 to 30 ring carbonatoms, substituted or unsubstituted trialkylsilyl group, substituted orunsubstituted arylalkylsilyl group, substituted or unsubstitutedtriarylsilyl group, substituted or unsubstituted diaryl phosphine oxidegroup, substituted or unsubstituted aromatic hydrocarbon group having 6to 30 ring carbon atoms, and substituted or unsubstituted heterocyclicgroup having 5 to 30 ring atoms, the substituted or unsubstitutedaromatic hydrocarbon group having 6 to 30 ring carbon atoms being anon-fused ring; Y₃₉ represents NR₃₃, an oxygen atom or a sulfur atom,R₃₃ being a substituent that is selected from the group consisting of acyano group, substituted or unsubstituted alkyl group having 1 to 20carbon atoms, substituted or unsubstituted cycloalkyl group having 3 to20 ring carbon atoms, substituted or unsubstituted alkoxy group having 1to 20 carbon atoms, substituted or unsubstituted aryloxy group having 6to 30 ring carbon atoms, substituted or unsubstituted alkylthio grouphaving 1 to 20 carbon atoms, substituted or unsubstituted arylthio grouphaving 6 to 30 ring carbon atoms, substituted or unsubstitutedalkylsilyl group having 3 to 50 carbon atoms, substituted orunsubstituted arylsilyl group having 6 to 50 ring carbon atoms,substituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, and substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, the substituted or unsubstituted aromatichydrocarbon group having 6 to 30 ring carbon atoms being a non-fusedring; Y₄₉ and Y₅₉ each independently represent NR₃₈, an oxygen atom or asulfur atom, R₃₈ being each independently a hydrogen atom or asubstituent, the substituent being selected from the group consisting ofa halogen atom, cyano group, substituted or unsubstituted alkyl grouphaving 1 to 20 carbon atoms, substituted or unsubstituted cycloalkylgroup having 3 to 20 ring carbon atoms, substituted or unsubstitutedalkoxy group having 1 to 20 carbon atoms, substituted or unsubstitutedaryloxy group having 6 to 30 ring carbon atoms, substituted orunsubstituted alkylthio group having 1 to 20 carbon atoms, substitutedor unsubstituted arylthio group having 6 to 30 ring carbon atoms,substituted or unsubstituted alkylsilyl group having 3 to 50 carbonatoms, substituted or unsubstituted arylsilyl group having 6 to 50 ringcarbon atoms, substituted or unsubstituted aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms, and substituted or unsubstitutedheterocyclic group having 5 to 30 ring atoms, the substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms being a non-fused ring; and a wavy line shows a bonding positionwith another atom or another structure in the molecule of the thirdmaterial. 2: The organic electroluminescence device according to claim1, wherein Y₃₉ and Y₄₉ are each independently an oxygen atom or a sulfuratom. 3: The organic electroluminescence device according to claim 1,wherein R₃₁ is a hydrogen atom or a substituent, the substituent beingselected from the group consisting of a halogen atom, cyano group,substituted or unsubstituted alkyl group having 1 to 30 carbon atoms,substituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, and substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms. 4: The organic electroluminescence deviceaccording to claim 1, wherein R₃₁ is a hydrogen atom, cyano group,substituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, or substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms. 5: The organic electroluminescence deviceaccording to claim 1, wherein X₃₁, X₃₂, X₃₄ and X₃₆ are eachindependently CR₃₁. 6: The organic electroluminescence device accordingto claim 1, wherein R₃₂ is a hydrogen atom or a substituent, thesubstituent being selected from the group consisting of a halogen atom,cyano group, substituted or unsubstituted alkyl group having 1 to 30carbon atoms, substituted or unsubstituted aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms, and substituted or unsubstitutedheterocyclic group having 5 to 30 ring atoms. 7: The organicelectroluminescence device according to claim 1, wherein R₃₂ is ahydrogen atom or substituted or unsubstituted alkyl group having 1 to 30carbon atoms. 8: The organic electroluminescence device according toclaim 1, wherein Y₃₁ to Y₃₁ are each independently CR₃₂. 9: The organicelectroluminescence device according to claim 1, wherein the thirdmaterial is an aromatic hydrocarbon compound. 10: The organicelectroluminescence device according to claim 1, wherein the thirdmaterial is an aromatic heterocyclic compound. 11: The organicelectroluminescence device according to claim 1, wherein a singletenergy EgS(M2) of the second material is larger than a singlet energyEgS(M1) of the first material. 12: The organic electroluminescencedevice according to claim 1, wherein an energy gap Eg_(77K)(M2) at 77 Kof the second material is larger than an energy gap Eg_(77K)(M1) at 77Kof the first material, and an energy gap Eg_(77K)(M3) at 77 K of thethird material is larger than the energy gap Eg_(77K)(M2) at 77 K of thesecond material. 13: The organic electroluminescence device according toclaim 1, wherein a difference ΔST(M2) between a singlet energy EgS(M2)of the second material and an energy gap Eg_(77K)(M2) at 77 K of thesecond material satisfies a relationship of a numerical formula(Numerical Formula 1) below,ΔST(M2)=EgS(M2)−Eg _(77K)(M2)<0.3 [eV]  Numerical Formula
 1. 14: Theorganic electroluminescence device according to claim 1, wherein adifference ΔST(M3) between a singlet energy EgS(M3) of the thirdmaterial and an energy gap Eg_(77K)(M3) at 77 K of the third materialsatisfies a relationship of numerical formula (Numerical Formula 3)below,ΔST(M3)=EgS(M3)−Eg _(77K)(M3)>0.3 [eV]  Numerical Formula
 3. 15: Theorganic electroluminescence device according to claim 1, wherein anenergy gap Eg_(77K)(M3) at 77K of the third material is 2.9 eV or more.16: The organic electroluminescence device according to claim 1, whereinan ionization potential Ip(M3) of the third material and an ionizationpotential Ip(M2) of the second material preferably satisfy arelationship of a numerical formula (Numerical Formula 4) below:Ip(M3)≥Ip(M2)  (Numerical Formula 4). 17: The organicelectroluminescence device according to claim 1, wherein an ionizationpotential Ip(M3) of the third material is 6.3 eV or more. 18: Theorganic electroluminescence device according to claim 1, wherein anelectron affinity Af(M3) of the third material is 2.8 eV or more. 19:The organic electroluminescence device according to claim 1, wherein adifference ΔST(M1) between a singlet energy EgS(M1) of the firstmaterial and an energy gap Eg_(77K)(M1) at 77 K of the first materialsatisfies a relationship of a numerical formula (Numerical Formula 2)below:ΔST(M1)=EgS(M1)−Eg _(77K)(M1)>0.3 [eV]  Numerical Formula
 2. 20: Theorganic electroluminescence device according to claim 1, wherein theemitting layer comprises no phosphorescent metal complex. 21: Theorganic electroluminescence device according to claim 1, wherein thefirst material emits a fluorescent light with a main peak wavelength of550 nm or less. 22: The organic electroluminescence device according toclaim 1, wherein the first material emits a fluorescent light with amain peak wavelength of 480 nm or less. 23: The organicelectroluminescence device according to claim 1, wherein the firstmaterial is at least one compound selected from the group consisting ofa pyrene derivative, an aminoanthracene derivative, an aminochrysenederivative, an aminopyrene derivative, a fluoranthene derivative, afluorene derivative, a diamine derivative, a triarylamine derivative anda styrylamine derivative. 24: An electronic device comprising theorganic electroluminescence device according to claim 1.